minta jawabannya kaka

Aturan sinus

sin C/AB = sin B/AC
sin C = AB. sin B/ AC
sin C = (10. 4/5) /(12) = 8/12 = 2/3

cos C = √(1 - sin² C) = √(1 - (2/3)² = √(1- 4/9) = √(5/9)
cos C = 1/3 √5