Question

find the values of x in the interval [0, 2pie] that satisfies the equation 2cos(x) + sin(2x) = 0

Answer 1

Do you know that sin(2x) = 2sin(x)cos(x) ?

Answer 2

That's the hint.

Answer 3

yes but I don't see how that helps that makes the equation 2cosx+2sinxcosx=0

Answer 4

2cos(x)[1+sin(x)] = 0

2cos(x) = 0
1+sin(x) = 0