nilai x yang mengakibatkan fungsi f(x) = sin^2 x - 2 sin x + 1 bernilai nol adalah...

f(x) = 0
sin^2 x - 2sin x + 1 = 0
(sin x - 1)(sin x - 1) = 0
(sin x - 1)^2 = 0
sin x - 1 = 0
sin x = 1

sin x = sin90°
x = 90°