tolong jawab nomer 8 sampai 10 terima kasih

trigonometri

8.
sin x/(1-cos x) + (1+cos x)/(sin x) =
= (sin x (sin x) + (1+cos x )(1 - cos x)) / (sin x ( 1 - cos x))
= ( sin² x + 1 - cos² x) / sin x (1 - cos x)
= (sin² x + sin² x) / (sin x (1 - cos x))
= ( 2 sin² x)/(sin x(1 - cos x))
= 2 sin x /(1 - cos x)
= ( 2 sin 1/2 x cos 1/2x)  /(2 sin² 1/2  x)
=  cos 1/2 x  / sin 1/2 x
= cot 1/2 x

9.  3 cos⁴  x + 6 sin² x =
= 3 cos⁴ x + 6 ( 1- cos² x)
= 3 cos⁴ x - 6 cos² x + 6
= 3(cos⁴ x - 2 cos² x + 2)

10.
(2 sin x cos x)/ cos x + 2/sec² x =
(2 sin x  + 2 /(1/cos x)²
= 2sin x + 2cos² x