Question

Bantuin dong yg jago matematika (trigonometri)
1.
Diket : AC = 10
/_ A = 30
/_ B = 45
Dit : panjang BC = ?

2.
Dik :
PR = 7
RQ = 3
PQ = 8
Cos Q = ?

Answer 1

1) aturan sinus
BC /sin ∠A  = AC/sin ∠B
BC = sin ∠A/ sin ∠B x AC
BC = sin 30 / sin 45 x 10
BC = (1/2 x 10 )/ (1/2 √2) = 10/√2 = 5√2

2) aturan cosinus
Cos Q = (PQ² + RQ² - PR²)/ ( 2 (PQ)(RQ)
Cos Q = (8² +3² - 7²) / ( 2. 8. 7) = 24/112 = 3/14

Answer 2

1. pake aturan sinus
AC/sin B = BC/ sin A
10/sin45° = BC/ sin30°
10/(√2/2) = BC/(1/2)
BC = 5√2
².