SOLUTION: Given that sinx = 3/5 and cosy = 7/25, with x and y both being Quadrant I angles, find sin2y.

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Question 1138864: Given that sinx = 3/5 and cosy = 7/25, with x and y both being Quadrant I angles, find sin2y.
Answer by ikleyn(52906) About Me  (Show Source):
You can put this solution on YOUR website!
.

In order for to solve this problem and to answer this question,  you do not need the info related to sin(x) - it is  IRRELEVANT. 

sin(2y) = 2*sin(y)*cos(y)


    cos(y) = sqrt%281+-+sin%5E2%28y%29%29 = sqrt%281-%287%2F25%29%5E2%29 = sqrt%28%2825%5E2-7%5E2%29%2F25%5E2%29 = 24%2F25.


Therefore,


sin(2y) = 2*sin(y)*cos(y) = 2%2A%287%2F25%29%2A%2824%2F25%29 = 336%2F625.    ANSWER

Solved and completed.