tolong di jawab yg no 6 sama 9 yah mastah sekalian

6.
a) ingat (a-b)(a+b) = a² - b²
(tan x + sec x)(tan x - sec x)
= tan²x - sec²x
= -1
b) 1/1+cos x + 1/1-cos x
= (1 - cos x + 1 + cos x) / (1+cos x)(1 - cos x)
= 2 / 1 - cos²x
= 2 / sin²x
c) tan x - sec²x/tan x
= tan²x/tan x - sec²x/tan x
= (tan²x - sec²x)/tan x
= -1 / tan x
d) (cos x / 1+sin x) + (1+sin x / cos x)
{cos x(cos x) + (1+sin x)(1+sin x) / cos x(1+sin x)
= (cos²x + 1 + 2 sin x + sin²x) / cos x(1+sin x)
= (1 + cos²x+sin²x + 2 sin x) / cos x(1+sinx)
= 2 + 2 sin x / cos x(1+sin x)
= 2(1+sin x) / cos x(1 + sin x)
= 2 / cos x
udah dulu yah