How do you find all solutions of the equation in the interval [0,2pi)[0,2π) given sin^2x+2cosx=2sin2x+2cosx=2?

1 Answer
Jun 18, 2018

x=0

Explanation:

sin^2 x=1-cos^2 xsin2x=1cos2x
1-cos^2 x + 2 cos x = 21cos2x+2cosx=2
let A=cosxA=cosx
Now solve
-A^2+2A-1=0A2+2A1=0
-(A-1)^2=0(A1)2=0
A=cosx=1A=cosx=1
x=2npix=2nπ(n=integer number)
In the interval [0,2pi)[0,2π)
the only solution is
when n=0 x=0