Pada segitiga ABC panjang AB 6√3cm, BC= 6cm dan sudut A 30° , nilai cos c adalah.....

AB/(sin C) = BC/(sin A)
6√3/(sin C) = 6/(sin 30°) ======> 6 coret
√3/(sin C) = 1/(1/2)
Sin C = 1/2 √3
Sin C = sin 60°
C = 60°
Cos C = cos 60° = 1/2