sin x cos x ( tan x - 1) = 0
so one solution is tan x = 1 giving x = 45, 225 degrees ( for x 0 to 360)
sin x cos x = 0 so either sinx = 0 giving x = 0, 180, 360 degrees
or cos x = 0 giving x = 90, 270
answer is 0, 45, 90, 180, 225, 270, 360 degrees ( for 0 =< x >= 360)
