mohon jawabannya yaa

Gunakan identitas trigonometri (memang banyak, coba untuk dihafalkan ya wkwk). Salah satunya:

cos2x = 2cos²x - 1 = 1 - 2sin²x = cos²x - sin²x

cos2x = 2cos²x - 1
1 + cos 2x = 2cos²x

cos 2x = 1 - 2sin²x
2sin²x = 1 - cos2x

*masukkan ke soal:
(1 + cos2x) / (1 - cos 2x)
= 2cos²x / 2sin²x [*coret 2 nya]
= cos²x / sin²x [*jabarkan kuadratnya]
= (cos x . cos x) / (sin x . sin x)
[*jika sin/cos = tan, maka cos/sin = 1/(sin/cos) = 1/tan]
= (1/tan x) . (1/tan x) [* 1/tan = cot]
= cot x . cot x
= cot²x ✔