#LyX 1.6.3 created this file. For more info see http://www.lyx.org/ \lyxformat 345 \begin_document \begin_header \textclass scrartcl \begin_preamble \date{} \usepackage{euler} \end_preamble \use_default_options true \language english \inputencoding auto \font_roman palatino \font_sans helvet \font_typewriter courier \font_default_family default \font_sc false \font_osf false \font_sf_scale 100 \font_tt_scale 100 \graphics default \paperfontsize 10 \spacing single \use_hyperref true \pdf_bookmarks true \pdf_bookmarksnumbered false \pdf_bookmarksopen false \pdf_bookmarksopenlevel 1 \pdf_breaklinks false \pdf_pdfborder true \pdf_colorlinks true \pdf_backref false \pdf_pdfusetitle true \papersize letterpaper \use_geometry true \use_amsmath 1 \use_esint 1 \cite_engine basic \use_bibtopic false \paperorientation portrait \leftmargin 3cm \topmargin 3cm \rightmargin 3cm \bottommargin 3cm \secnumdepth -1 \tocdepth 0 \paragraph_separation skip \defskip medskip \quotes_language english \papercolumns 1 \papersides 1 \paperpagestyle default \tracking_changes false \output_changes false \author "" \author "" \end_header \begin_body \begin_layout Title Math Trigonometry Review \end_layout \begin_layout Author CHSN Review Project \end_layout \begin_layout Publishers \begin_inset Graphics filename ccbysa.png scale 50 \end_inset \end_layout \begin_layout Standard \SpecialChar \textcompwordmark{} \end_layout \begin_layout Standard This review guide was written by Dara Adib. It was designed for a test on trigonometry administered by Jeanine Lennon to her Math 12H (4H/Precalculus) class on February 12, 2008, but also applies to trigonometry material in Math 11H (3H). \end_layout \begin_layout Standard This is a development version of the text that should be considered a work-in-pr ogress. \end_layout \begin_layout Standard This review guide and other review material are developed by the CHSN Review Project. \end_layout \begin_layout Standard Copyright © 2008-2009 Dara Adib. This is a freely licensed work, as explained in the Definition of Free Cultural Works ( \begin_inset Flex URL status collapsed \begin_layout Plain Layout freedomdefined.org \end_layout \end_inset ). It is licensed under the Creative Commons Attribution-Share Alike 3.0 United States License. To view a copy of this license, visit \begin_inset Flex URL status collapsed \begin_layout Plain Layout http://creativecommons.org/licenses/by-sa/3.0/us/ \end_layout \end_inset or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. \end_layout \begin_layout Standard This review guide is provided \begin_inset Quotes eld \end_inset as is \begin_inset Quotes erd \end_inset without warranty of any kind, either expressed or implied. You should not assume that this review guide is error-free or that it will be suitable for the particular purpose which you have in mind when using it. In no event shall the CHSN Review Project be liable for any special, incidental , indirect or consequential damages of any kind, or any damages whatsoever, including, without limitation, those resulting from loss of use, data or profits, whether or not advised of the possibility of damage, and on any theory of liability, arising out of or in connection with the use or performanc e of this review guide or other documents which are referenced by or linked to in this review guide. \end_layout \begin_layout Standard \begin_inset Newpage newpage \end_inset \end_layout \begin_layout Section Angles and Sectors of Circles \end_layout \begin_layout Subsection Radians \end_layout \begin_layout Itemize To convert degrees to radians, multiply by \begin_inset Formula $\frac{\pi}{180}$ \end_inset . \end_layout \begin_layout Itemize To convert radians to degrees, multiply by \begin_inset Formula $\frac{180}{\pi}$ \end_inset . \end_layout \begin_layout Itemize One radian equals \begin_inset Formula $\frac{180}{\pi}$ \end_inset or approximately \begin_inset Formula $57.296^{\circ}$ \end_inset . \end_layout \begin_layout Subsection Coterminal Angles \end_layout \begin_layout Description coterminal \begin_inset space ~ \end_inset angles different angles that have the same initial and terminal ray \end_layout \begin_layout Standard The differences between coterminal angles are multiples of \begin_inset Formula $360^{\circ}$ \end_inset . \end_layout \begin_layout Quote Examples: \begin_inset Formula $60^{\circ}$ \end_inset , \begin_inset Formula $-300^{\circ}$ \end_inset , \begin_inset Formula $420^{\circ}$ \end_inset \end_layout \begin_layout Subsection Sectors \end_layout \begin_layout Description sector part of a circle formed by two radii and an arc \end_layout \begin_layout Standard \begin_inset Formula $s=r\theta$ \end_inset ( \begin_inset Formula $\textrm{arc\, length}=\textrm{radius}\times\textrm{angle}$ \end_inset ) \end_layout \begin_layout Standard The angle must be represented in radians. \end_layout \begin_layout Description apparent \begin_inset space ~ \end_inset size the angle that an object subtends at one's eyes; this explains why an object appears to be smaller when farther away \end_layout \begin_layout Section Trigonometric Functions \end_layout \begin_layout Subsection Reciprocal Functions \end_layout \begin_layout Standard The following are reciprocal functions. \end_layout \begin_layout Itemize \begin_inset Formula ${\displaystyle \csc x=\frac{1}{\sin x}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Itemize \begin_inset Formula ${\displaystyle \sec x=\frac{1}{\cos x}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Itemize \begin_inset Formula ${\displaystyle \cot x=\frac{1}{\tan x}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard As a result, the following are true as well. \end_layout \begin_layout Itemize \begin_inset Formula ${\displaystyle \sin x=\frac{1}{\csc x}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Itemize \begin_inset Formula ${\displaystyle \cos x=\frac{1}{\sec x}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Itemize \begin_inset Formula ${\displaystyle \tan x=\frac{1}{\cot x}}$ \end_inset \end_layout \begin_layout Subsection Cofunctions \end_layout \begin_layout Standard The following are cofunctions. \end_layout \begin_layout Itemize \begin_inset Formula $\sin x=\cos(90-x)$ \end_inset \end_layout \begin_layout Itemize \begin_inset Formula $\tan x=\cot(90-x)$ \end_inset \end_layout \begin_layout Itemize \begin_inset Formula $\sec x=\csc(90-x)$ \end_inset \end_layout \begin_layout Standard As a result, the following are true as well. \end_layout \begin_layout Itemize \begin_inset Formula $\cos x=\sin(90-x)$ \end_inset \end_layout \begin_layout Itemize \begin_inset Formula $\cot x=\tan(90-x)$ \end_inset \end_layout \begin_layout Itemize \begin_inset Formula $\csc x=\sec(90-x)$ \end_inset \end_layout \begin_layout Section Special Angles \end_layout \begin_layout Subsection Quadrantal Angles \end_layout \begin_layout Description quadrantal \begin_inset space ~ \end_inset angles angles that have a terminal side coinciding with a coordinate axis \end_layout \begin_layout Standard The value of the trigonometric function (i.e. sine, cosine, tangent) is determined by the coordinates of the points on a unit circle. By definition, the point \begin_inset Formula $(x,y)$ \end_inset on a unit circle corresponds to \begin_inset Formula $(\cos\theta,\sin\theta)$ \end_inset . \end_layout \begin_layout Standard As a result, quadrantal angles can be determined easily. Table \begin_inset CommandInset ref LatexCommand ref reference "tab:quadrantal-angles" \end_inset lists quadrantal angles and the values of trigonometric functions. Since \begin_inset Formula $\tan\theta=\frac{\sin\theta}{\cos\theta}$ \end_inset , the tangent function of an angle can be found by dividing the sine function of the angle by the cosine function of the angle. \end_layout \begin_layout Standard \noindent \align center \begin_inset Float table wide false sideways false status open \begin_layout Plain Layout \noindent \align center \begin_inset Tabular \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\theta$ \end_inset (degrees) \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\theta$ \end_inset (radians) \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout Point \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\sin\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\cos\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\tan\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(1,0)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $90^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula ${\displaystyle \frac{\pi}{2}}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(0,1)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $180^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula $\pi$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(-1,0)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $-1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $270^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula ${\displaystyle \frac{3\pi}{2}}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(0,-1)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $-1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \end_inset \end_layout \begin_layout Plain Layout \noindent \align center \begin_inset Tabular \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\theta$ \end_inset (degrees) \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\theta$ \end_inset (radians) \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout Point \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\cot\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\sec\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\csc\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(1,0)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $90^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula ${\displaystyle \frac{{\displaystyle \pi}}{2}}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(0,1)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $180^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula $\pi$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(-1,0)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $-1$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $270^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula ${\displaystyle \frac{3\pi}{2}}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $(0,-1)$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $0$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout undefined \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $-1$ \end_inset \end_layout \end_inset \end_inset \end_layout \begin_layout Plain Layout \begin_inset Caption \begin_layout Plain Layout \begin_inset CommandInset label LatexCommand label name "tab:quadrantal-angles" \end_inset quadrantal angles \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Subsection Angles greater than \begin_inset Formula $90^{\circ}$ \end_inset \end_layout \begin_layout Standard Angles greater than \begin_inset Formula $90^{\circ}$ \end_inset may be in different quadrants. The trigonometric functions vary over whether the trigonometric function of a certain angle is positive or negative. It is useful to remember the mnemonic device \begin_inset Quotes eld \end_inset All Students Take Calculus. \begin_inset Quotes erd \end_inset \end_layout \begin_layout Itemize All trigonometric functions are positive in the first quadrant \end_layout \begin_layout Itemize Sine and cosecant are positive in the second quadrant \end_layout \begin_layout Itemize Tangent and cotangent are positive in the third quadrant \end_layout \begin_layout Itemize Cosine and secant are positive in the fourth quadrant \end_layout \begin_layout Itemize The remaining trigonometric functions in each quadrant are negative. \end_layout \begin_layout Subsection Reference Angles \end_layout \begin_layout Standard The use of reference angles is a way to simplify the calculation of the values of trigonometric functions in different quadrants. Refer to Table \begin_inset CommandInset ref LatexCommand ref reference "tab:reference-angles" \end_inset , where \begin_inset Formula $\theta$ \end_inset is the angle (in degrees) and \begin_inset Formula $\beta$ \end_inset is the reference angle. \end_layout \begin_layout Standard \noindent \align center \begin_inset Float table wide false sideways false status open \begin_layout Plain Layout \noindent \align center \begin_inset Tabular \begin_inset Text \begin_layout Plain Layout Quadrant \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout Reference Angle ( \begin_inset Formula $\beta$ \end_inset ) \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout I \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\beta=\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout II \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\beta=180^{\circ}-\theta$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout III \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\beta=\theta-180^{\circ}$ \end_inset \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout IV \end_layout \end_inset \begin_inset Text \begin_layout Plain Layout \begin_inset Formula $\beta=360^{\circ}-\theta$ \end_inset \end_layout \end_inset \end_inset \end_layout \begin_layout Plain Layout \begin_inset Caption \begin_layout Plain Layout \begin_inset CommandInset label LatexCommand label name "tab:reference-angles" \end_inset reference angles \end_layout \end_inset \end_layout \end_inset \end_layout \begin_layout Section Sum and Difference Formulas \end_layout \begin_layout Subsection Sum Formulas \end_layout \begin_layout Subsubsection Sine \end_layout \begin_layout Standard \begin_inset Formula $\sin(A+B)=\sin A\cos B+\cos A\sin B$ \end_inset \end_layout \begin_layout Subsubsection Cosine \end_layout \begin_layout Standard \begin_inset Formula $\cos(A+B)=\cos A\cos B-\sin A\sin B$ \end_inset \end_layout \begin_layout Subsubsection Tangent \end_layout \begin_layout Standard The derivation for the tangent of the sum of two angles follows. \end_layout \begin_layout Standard \begin_inset Formula $\tan(A+B)$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula ${\displaystyle \frac{\sin(A+B)}{\cos(A+B)}}$ \end_inset \family default \series default \shape default \size default \emph default \bar default \noun default \color inherit \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula ${\displaystyle \frac{\sin A\cos B+\cos A\sin B}{\cos A\cos B-\sin A\sin B}}$ \end_inset \family default \series default \shape default \size default \emph default \bar default \noun default \color inherit \begin_inset VSpace bigskip \end_inset \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \frac{{\displaystyle \frac{\sin A\cos B}{\cos A\cos B}+\frac{\cos A\sin B}{\cos A\cos B}}}{{\displaystyle \frac{\cos A\cos B}{\cos A\cos B}-\frac{\sin A\sin B}{\cos A\cos B}}}}$ \end_inset \begin_inset VSpace bigskip \end_inset \end_layout \begin_layout Standard \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula ${\displaystyle \frac{\tan A+\tan B}{1-\tan A\tan B}}$ \end_inset \end_layout \begin_layout Subsection Difference Formulas \end_layout \begin_layout Subsubsection Sine \end_layout \begin_layout Standard \begin_inset Formula $\sin(A-B)=\sin A\cos B-\cos A\sin B$ \end_inset \end_layout \begin_layout Subsubsection Cosine \end_layout \begin_layout Standard \begin_inset Formula $\cos(A-B)=\cos A\cos B+\sin A\sin B$ \end_inset \end_layout \begin_layout Subsubsection Tangent \end_layout \begin_layout Standard The derivation for the tangent of the difference of two angles follows. \end_layout \begin_layout Standard \begin_inset Formula $\tan(A-B)$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula ${\displaystyle \frac{{\displaystyle \sin(A-B)}}{\cos(A-B)}}$ \end_inset \family default \series default \shape default \size default \emph default \bar default \noun default \color inherit \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula ${\displaystyle \frac{\sin A\cos B-\cos A\sin B}{\cos A\cos B+\sin A\sin B}}$ \end_inset \family default \series default \shape default \size default \emph default \bar default \noun default \color inherit \begin_inset VSpace bigskip \end_inset \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \frac{{\displaystyle \frac{\sin A\cos B}{\cos A\cos B}-\frac{\cos A\sin B}{\cos A\cos B}}}{{\displaystyle \frac{\cos A\cos B}{\cos A\cos B}+\frac{\sin A\sin B}{\cos A\cos B}}}}$ \end_inset \begin_inset VSpace bigskip \end_inset \end_layout \begin_layout Standard \family roman \series medium \shape up \size normal \emph off \bar no \noun off \color none \begin_inset Formula ${\displaystyle \frac{\tan A-\tan B}{1+\tan A\tan B}}$ \end_inset \end_layout \begin_layout Section Identities \end_layout \begin_layout Subsection Pythagorean Identities \end_layout \begin_layout Enumerate \begin_inset Formula $\sin^{2}\theta+\cos^{2}\theta=1$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Enumerate \begin_inset Formula $1+\tan^{2}\theta=\sec^{2}\theta$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Enumerate \begin_inset Formula $1+\cot^{2}\theta=\csc^{2}\theta$ \end_inset \end_layout \begin_layout Subsection Quotient Identities \end_layout \begin_layout Enumerate \begin_inset Formula ${\displaystyle \tan\theta=\frac{\sin\theta}{\cos\theta}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Enumerate \begin_inset Formula ${\displaystyle \cot\theta=\frac{\cos\theta}{\sin\theta}}$ \end_inset \end_layout \begin_layout Section Graphing Trigonometric Functions \end_layout \begin_layout Subsection General Form \end_layout \begin_layout Standard The general form of a trigonometric function is one of the following (sine or cosine). \end_layout \begin_layout Standard \begin_inset Formula $y=a\sin b(x\pm c)\pm d$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $y=a\cos b(x\pm c)\pm d$ \end_inset \end_layout \begin_layout Standard In other words, it can be understood to mean the following. \end_layout \begin_layout Standard \begin_inset Formula $y=\textrm{amplitude}\times\sin\,[\textrm{frequency}\,(x-\textrm{horizontal\, translation})]+\textrm{vertical\, translation}$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $y=\textrm{amplitude}\times\cos\,[\textrm{frequency}\,(x-\textrm{horizontal\, translation})]+\textrm{vertical\, translation}$ \end_inset \end_layout \begin_layout Standard A negative amplitude means a reflection over the \begin_inset Formula $x$ \end_inset -axis. The vertical translation may be kept in front only to prevent the ambiguity that the number may be part of the trigonometric function. \end_layout \begin_layout Subsection Frequency and Period \end_layout \begin_layout Standard The following statements are true regarding the relationship between frequency and period. \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \textrm{frequency}=\frac{2\pi}{\textrm{period}}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \textrm{period}=\frac{2\pi}{\textrm{frequency}}}$ \end_inset \begin_inset VSpace medskip \end_inset \end_layout \begin_layout Subsection Sine and Cosine \end_layout \begin_layout Standard The sine function follows the form zero, maximum, zero, minimum, before any translation. \end_layout \begin_layout Standard The cosine function follows the form maximum, zero, minimum, zero, before any translation. \end_layout \begin_layout Standard As a result, sine and cosine are horizontal translations of each other. \end_layout \begin_layout Section Double and Half Angle Formulas \end_layout \begin_layout Subsection Double Angle Formulas \end_layout \begin_layout Standard The following are determined by plugging in an angle twice into the sum formulas. \end_layout \begin_layout Subsubsection Sine \end_layout \begin_layout Standard \begin_inset Formula $\sin2A=2\sin A\cos A$ \end_inset \end_layout \begin_layout Subsubsection Cosine \end_layout \begin_layout Standard \begin_inset Formula $\cos2A=\cos^{2}A-\sin^{2}A$ \end_inset \end_layout \begin_layout Paragraph More Cosine Formulas \end_layout \begin_layout Standard However, more formulas for the double of an angle with cosine can be determined since \begin_inset Formula $\sin^{2}A+\cos^{2}A=1$ \end_inset (first Pythagorean identity). \end_layout \begin_layout Standard \begin_inset Formula $\cos2A=1-2\sin^{2}A$ \end_inset \end_layout \begin_layout Standard \begin_inset Formula $\cos2A=2\cos^{2}A-1$ \end_inset \end_layout \begin_layout Subsubsection Tangent \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \tan2A=\frac{2\tan A}{1-\tan^{2}A}}$ \end_inset \end_layout \begin_layout Subsection Half Angle Formulas \end_layout \begin_layout Subsubsection Sine \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \sin\frac{1}{2}A=\pm\sqrt{\frac{1-\cos A}{2}}}$ \end_inset \end_layout \begin_layout Subsubsection Cosine \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \cos\frac{1}{2}A=\pm\sqrt{\frac{1+\cos A}{2}}}$ \end_inset \end_layout \begin_layout Subsubsection Tangent \end_layout \begin_layout Standard \begin_inset Formula ${\displaystyle \tan\frac{1}{2}A=\pm\sqrt{\frac{1-\cos A}{1+\cos A}}}$ \end_inset \end_layout \end_body \end_document