Question

Kak tolong bantu jawab dong nomor 11......
pliss kkaakk
besok dikumpul
harus ada penyelesaiannya yaaa

Answer 1

Verified answer

•

Ralat soal → 8 cos 2x

t = 1/2 x → x = 2t

cos 2x = cos 4t = 1 - 2 sin² 2t

••

8 cos 2x + 6 sin x - 7 = 0

8(1 - 2 sin² 2t) + 6 sin 2t - 7 = 0

16 sin² 2t - 6 sin 2t - 1 = 0

(8 sin 2t + 1)(2 sin 2t - 1) = 0

sin 2t = -1/8 → kuadran 3 dan 4 → tdk memenuhi interval

2 sin 2t - 1 = 0

sin 2t = 1/2

2t = 30° + k.360°

t = 15° + k.180°

atau

2t = 150° + k.360°

t = 75° + k.180°

k bilangan bulat

Nilai t yg memenuhi interval 0° ≤ x ≤ 180° :

15° dan 75°