what are the zeroes of the graph 2sin(squared)x + cosx-3 = 0
Write it as a polynomial in cosx and solve for cosx.
2(1 - cos^2x) + cosx = 0
2 cos^2x -cosx -2 = 0
That can be factored to give
(2cosx +1)(cosx -1) - 0
cosx = -1/2 or +1
2(1 - cos^2x) + cosx = 0
2 cos^2x -cosx -2 = 0
That can be factored to give
(2cosx +1)(cosx -1) - 0
cosx = -1/2 or +1