poin banyak.berserta caranya

segitiga aturan sinus dan cosinus

16.ΔPQR, <Q= 60°, <R = 75°
<P = 180 -60- 75 = 45
P < Q < R
sisi terpendek didepan <P = sisi QR

QR/sin P =PR /sin Q
QR =(PR.sin P)/(sin Q)
QR = 10√6 (sin 45) / sin 60 = 10√6 (1/2√2) /(1/2 √3)
QR= 10√12/(√3) = 10.2 √3/√3 = 20

17. ΔABC
<B = 30 , <C=120, <A =180-30-120= 30
<A = <B = 30 , ΔABC sama kaki  AC = BC = a= b

a+b +c = 10
a+ a+ c= 10
2a =10 - c
a= 5 - 1/2 c .....(1)

c/sin C = a/sin A
c = a. sin C/sin A
c = a sin 120 /sin 30
c = a.1/2 √3 /(1/2)
c = a√3.....(2)

(1) sub ke (2)
c= (5 - 1/2 c)√3
c  = 5√3 - 1/2 c√3
c+ 1/2 c√3 = 5√3 ....kali2
2c + c√3 = 10√3
c(2 + √3) = 10√3
c = 10√3 /(2 +√3)
c = 20√3 + 30