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I need help 😢

Solve for 0 ≤ y < 360o:
5 sin²3y − 11 cos 3y = 0
Reply 1
There are quite a few steps to this, how much progress did you make?

For instance, a possible first step would be to express the whole equation in terms of either sines or cosines. Why? Well... if you don't know please ask.

But, if you happen to know how to expand cos(3y), please don't do that. (If you don't know, just ignore this throwaway comment).
Reply 2
Original post by Alaa Ibrahim
Solve for 0 ≤ y < 360o:
5 sin²3y − 11 cos 3y = 0

Hi!
Use the fact that sin² (3y) = 1 - cos² (3y).
You will get a quadratic equation whose roots will be equal to cos 3y.
Solve for y then! Hope it helps:smile:

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