SOLUTION: Hope you can help me: Solve sin2y = cos4y for y, where 0 <= y

SOLUTION: Hope you can help me: Solve sin2y = cos4y for y, where 0 <= y < 360

Question 62148: Hope you can help me:
Solve sin2y = cos4y for y, where 0 <= y < 360
Answer by joyofmath(189) (Show Source): You can put this solution on YOUR website!
Solve sin2y = cos4y for y, where 0 <= y < 360
Let x = 2y. Then, .
There's a trig identity:
We use that identity and get:
Let some variable, say g, = sinx.
Then, .
Or,
Or, .
This factors into .
So, or .
So, since , or .
Since x = 2y, or .
So, 2y = 270 degress or 2y = 30 degrees.
So, the answer is y = 135 degrees or y = 15 degrees.
Let's verify the answer:
sin(2*135) = sin(270) = -1 and cos(4*135) = cos(540) = cos(180) = -1.
sin(2*15) = sin(30) = 1/2 and cos(60) = 1/2.
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