tolong ya kk. terima kasih

Mapel: Matematika
Bab: Trigonometri

π/6 = 180°/6 = 30°

f(x) = (cos x)^2 + cos 2x sin x
f(30°) = (cos 30°)^2 + cos 2(30°) sin 30°
= (✓3/2)^2 + (1/2 x 1/2)
= 3/4 + 1/4
= 4/4
= 1

Jadi jawaban yang tepat adalah B. 1

[tex]f( \frac{\pi}{6} ) = cos {}^{2} ( \frac{\pi}{6} ) + cos \: 2( \frac{\pi}{6} )sin( \frac{\pi}{6}) \\ = cos {}^{2} ( \frac{\pi}{6} ) + cos (\frac{\pi}{3} )sin \: \frac{\pi}{6} \\ = (\frac{1}{2} \sqrt{3} ) {}^{2} + \frac{1}{2} . \frac{1}{2} \\ = \frac{1}{4} .3 + \frac{1}{4} \\ = \frac{3}{4} + \frac{1}{4} \\ = \frac{4}{4} \\ = 1[/tex]
semoga membantu
ikuti yah