gunakan rumus perkalian a. 4sin45°cos15° b. sin75°cos15°

Product Formulas.

Answer for problem a.
sin α cos β = 1/2 [sin (α + β) + sin (α - β)]
4 sin 45° cos 15° = 2 [sin (45° + 15°) + sin (45° - 15°)]
= 2 (1/2 √3 + 1/2)
= 1 + √3

Answer for problem b.
sin 75° cos 15° = 1/2 [sin (75° + 15°) + sin (75° - 15°)]
= 1/2 (1 + 1/2 √3)
= 1/4 (2 + √3)