Question

Tolong cara & jawabannya dr kedua soal Trigonometri di atas. Makasih :)

Answer 1

A)
Sin (5π/12) × cos(π/12)
Sin (5.180/12) × cos(180/12)
Sin 75° × cos 15°
*gunakan rumus trigonometri
2sinAcosB = sin(A+B)+sin(A-B)
SinAcosB = (1/2)(sin[A+B]+sin[A-B])
sin75°cos15° = (1/2)(sin[75+15]+sin[75-15])
~~~~~~~~~~ = (1/2)(sin90° + sin60°)
~~~~~~~~~~ = (1/2)(1+√3/2)
~~~~~~~~~~ = 1/2 + √3/4

B)
= cos(11π/6) × cos(π/6)
= cos(11.180/6) × cos(180/6)
= cos 330° × cos 30°
= sin(270+60) × cos 30°
= sin 60° × cos 30°
= (√3/2) × (√3/2)
= (√3/2)²
= 3/4