Question

Nilai dari 8. sin 165°.cos 15°

Answer 1

2 sin a cos b = sin (a + b) + sin (a - b)

•••
8 sin 165 cos 15
= 4 . 2 sin 165 cos 15
= 4 (sin (165 + 15) + sin (165 - 15))
= 4 (0 + 1/2)
= 2