Solve for all solutions 0-2pi
1) Sin2xSinx-Cos2xCosx= -cosx
2) Sec^2x = 4tan^2x
3) cos(pi-x) +sin(x-pi/2) = 1
8) 2cos^2x=1
1
sin^2x sinx = -cos x + cos^2x cosx ( I will drop the 'x' for easier typing)
= -cos ( 1- cos^2)
sin^2 sin = -cos (sin^2)
sin = - cos
x = 3pi / 4 and 7pi/4
8)
2 cos^2 = 1
cos^2 = 1/2
cos = +- sqrt (1/2) = +-.707 pi/4 3pi/4 5pi/4 7pi/4