Question

Teman bantu jawab soal no 15,19,21, dan 23 yang bisa jawab bantu dong.. nanti aku kasih jawaban terbaikkkkkkk. makasih

Answer 1

15. cos 2x - sin x = 0
cos 2x = sin x
1-2 sin² x = sin x mm
2 sin²x + sin x - 1 = 0
( 2 sin x - 1)(sin x + 1) = 0
sin x = 1/2 atau sin x = -1
x = 30, 150 atau x = 270

ubah ke bentuk radian
30 = 30/180 π = π/6
150 = 150/180 π = 5π / 6
270 = 270/180 π = 3π / 2

HP { π/6, 5π/6, 3π/2)


17.cos A = AB²+AC²-BC² / 2.AB.AC
= 9²+8²-7² / 2.9.8
= 96 / 144
= 2/3

shngga sin A = √(3²-2²) / 3
= 1/3 √5

21. sin A / BC = sin B / AC
sin A / 4 = sin 45 / 8
sin A = 4.sin 45 / 8
= √2/4
cos A = 14/4 = 7/2

tan BAC = sin A/ cos A
= 1/14 √2

23. L ABC = 1/2. AB.AC sin A
= 1/2. 2.6. sin 30
= 3

no.19. Soal silahkan upload kembali