tolong dibantuuuuuuuuuuuuu

2a.
( 1 - cos x )² - ( 1 + cos x )²
=((1 - cos x + 1 + cos x) . (1 - cos x - (1 + cos x)))
=(2) . -2 cos x = -4 cos x

2b.
( 1 - sin x ) ( 1 + sin x ) = 1 - sin² x = cos² x

3.
cos 30° = x / 8
½√3 = x / 8
x = 8 . ½√3
x = 4√3 meter