Recent content by Aly Ren

how to solve cos(2a) - cos(4a) =0 cos2a - cos4a=0 cos2a - 2 cos^2(2a)-1 =0 set cos2a = y y - 2y^2 -1 = 0 change sign 2y^2 - y + 1 =0 is this factor-able? stuck on this step!