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wu :: forums    riddles    easy (Moderators: Eigenray, Icarus, towr, william wu, SMQ, ThudnBlunder, Grimbal)    Trig Problem « Previous topic | Next topic » Pages: 1  Reply Notify of replies Send Topic Print    Author  Topic: Trig Problem  (Read 3977 times) warriors837 Guest Trig Problem   trig9.gif « on: May 26th, 2009, 11:20am » Quote Modify Remove A twenty foot ladder leans up against a perpendicular wall and just touches the outer top edge of a 6'x6'x6' cube packing case pushed up close to the wall. How far up the wall is the top of the ladder?   « Last Edit: May 26th, 2009, 11:46am by warriors837 » IP Logged towr wu::riddles Moderator Uberpuzzler Some people are average, some are just mean.     Gender: Posts: 13730 Re: Trig Problem   « Reply #1 on: May 26th, 2009, 12:01pm » Quote Modify Let's call the length from the cube to the foot of the ladder a, then the height h, is (6+a) * 6/a, and we have the further constraint that h2+(6+a)2 = 202. I think that should be enough. IP Logged Wikipedia, Google, Mathworld, Integer sequence DB pex Uberpuzzler     Gender: Posts: 880 Re: Trig Problem   « Reply #2 on: May 26th, 2009, 2:31pm » Quote Modify on May 26th, 2009, 12:01pm, towr wrote: Let's call the length from the cube to the foot of the ladder a, then the height h, is (6+a) * 6/a, and we have the further constraint that h2+(6+a)2 = 202. I think that should be enough. Yes it is, but I think the solution outlined here (with different numbers) is aesthetically preferable. (Although it uses the same general ideas.) IP Logged ThudnBlunder wu::riddles Moderator Uberpuzzler The dewdrop slides into the shining Sea     Gender: Posts: 4489 Re: Trig Problem   « Reply #3 on: May 26th, 2009, 8:32pm » Quote Modify See also   http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_eas y;action=display;num=1216424120;   http://www.ocf.berkeley.edu/~wwu/cgi-bin/yabb/YaBB.cgi?board=riddles_med ium;action=display;num=1216427247; IP Logged THE MEEK SHALL INHERIT THE EARTH.....................................................................er, if that's all right with the rest of you. Wiles_euler Guest Re: Trig Problem   proof.doc « Reply #4 on: May 28th, 2009, 4:02pm » Quote Modify Remove Work and answers in attachment « Last Edit: May 29th, 2009, 7:44am by warriors837 » IP Logged pex Uberpuzzler     Gender: Posts: 880 Re: Trig Problem   « Reply #5 on: May 29th, 2009, 12:26am » Quote Modify on May 28th, 2009, 4:02pm, Wiles_euler wrote: Full proof in attachment... I wouldn't call that a full proof... What it's basically saying is, we have h = (6+a)*6/a and h2+(6+a)2=202, so let's numerically solve ((6+a)*6/a)2+(6+a)2=202.   Have you considered reading ThudanBlunder's and my links?   Edit: Besides, why would you go through all the simplification if you're going to solve the equation numerically anyway? 202=h2+[6+(36/(h-6)]2 isn't really any harder for a numerical solver than 400=(h4-12h3+72h2)/(h2-12h+36)... « Last Edit: May 29th, 2009, 12:31am by pex » IP Logged towr wu::riddles Moderator Uberpuzzler Some people are average, some are just mean.     Gender: Posts: 13730 Re: Trig Problem   « Reply #6 on: May 29th, 2009, 12:33am » Quote Modify It's not only not a full proof, but I'm fairly sure the answers aren't even quite correct (even besides the fact they're both approximations). They're not very far off, but still too far to be accurate. Just put them back into the equation, you won't get 400, but 401 and 413. « Last Edit: May 29th, 2009, 12:38am by towr » IP Logged Wikipedia, Google, Mathworld, Integer sequence DB Wiles_euler Guest Re: Trig Problem   « Reply #7 on: May 29th, 2009, 7:45am » Quote Modify Remove When you plug in the given values from the attachment, they do work out with the us of the Pythagorean theorem. « Last Edit: May 29th, 2009, 7:46am by warriors837 » IP Logged Ronno Junior Member     Gender: Posts: 140 Re: Trig Problem   « Reply #8 on: May 29th, 2009, 8:45pm » Quote Modify I don't think that statement makes any sense and the correct values are around 9.040515497 and 17.84009752. IP Logged Sarchasm: The gulf between the author of sarcastic wit and the person who doesn't get it.. towr wu::riddles Moderator Uberpuzzler Some people are average, some are just mean.     Gender: Posts: 13730 Re: Trig Problem   « Reply #9 on: May 30th, 2009, 2:14am » Quote Modify on May 29th, 2009, 8:45pm, Ronno wrote: I don't think that statement makes any sense and the correct values are around 9.040515497 and 17.84009752. Yup, that's what I get. Or to be exact: 3 + (109) +/- (82 - 6 (109))   But hey, it's his homework; so by all means he should go with his own results IP Logged Wikipedia, Google, Mathworld, Integer sequence DB Pages: 1  Reply Notify of replies Send Topic Print Forum Jump: ----------------------------- riddles -----------------------------=> easy   - medium   - hard   - what am i   - what happened   - microsoft   - cs   - putnam exam (pure math)   - suggestions, help, and FAQ   - general problem-solving / chatting / whatever ----------------------------- general -----------------------------  - guestbook   - truth   - complex analysis   - wanted   - psychology   - chinese « Previous topic | Next topic »

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