Question: where are sinx and cosx equal?
Answer: From the unit circle we see that sin x and cos x can only have the same value in two places, in x = /4 and x = 5 /4 (45° and 225°). The equation sin x = cos x can also be solved by dividing through by cos x. If we put k = 0 and k = 1 we get the solutions /4 (45°) and /4 + = 5 /4 (45°+ 180°= 225°).