Respuesta :

a) sin 15° = (opposite side)/(hypotenuse)

sin 15° = x/20, but sin 15° = 0.25881
0.25881 = x/20 → x = 0.25881.(20) → x = 5.17
 
b) cos Ф° = adjacent side/hypotenuse

cos Ф° = 10/11 → cos Ф° = 0.9090.

cos⁻¹(0.9090) = Ф°  → Ф° = 24.62°