SOLUTION: What's the Exact Value for Sin 390 degrees ? Without using a calculator

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Question 577615: What's the Exact Value for Sin 390 degrees ? Without using a calculator
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
390%5Eo=360%5Eo%2B30%5Eo, so sin%28390%5Eo%29=sin%2830%5Eo%29.
sin%2830%5Eo%29=1%2F2.
I remember that, but I can also prove it out of a right triangle:
Suppose you have a right triangle ABC, with the right angle at C and a 30%5Eo%29 angle at A. That triangle is half of an equilateral triangle.
so sin%2830%5Eo%29=sin%28BAC%29=BC%2FAB=1%2F2