SOLUTION: Solve: {{{sin2x=cosx}}}, {{{-2pi<=x<=pi}}}

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Question 553053: Solve:
,
Found 2 solutions by Alan3354, solver91311:
Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website!
Solve:
,
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2sinx*cosx = cosx
2sinx*cosx - cosx 0
cos(x)*(2sin(x) - 1) = 0
cos(x) = 0
x = pi/2, -pi/2, -3pi/2
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2sin(x) = 1
sin(x) = 1/2
x = -11pi/6, -7pi/6, pi/6, 5pi/6

Answer by solver91311(24713) (Show Source):
You can put this solution on YOUR website!

Since we can write:

Multiply by

Use the unit circle, recalling that sin of the angle is the -coordinate of the point of intersection of the terminal ray with the unit circle and find all angles where in your given interval. Note that the given interval is one and a half trips around the circle. Hint: start at and go backwards.

John

My calculator said it, I believe it, that settles it