Triangle Area - Quasi-Simple

In the following diagram, let us say that we are interested in only the area of the blue triangle as the points B and D rotate about A in a circular fashion. You are given that D, B, and A are collinear, BA = 30, and DB = 45. It takes point B 10 seconds to travel around the entire circle.

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Mimi Yang, July 27, 2010, Created with GeoGebra