Diketahui segitiga KLM, KL = 15 cm, LM = 13cm , MK =8cm. nilai sin L

MK² = KL² + LM² - 2(KL)(LM) cos L
64 = 225 + 169 - 390 cos L
390 cos L = 330
cos L = 11/13

sisi samping = 11
sisi miring = 13
sisi depan = 4 akar 3

sin L = 4/13 akar 3

Mapel : Matematika
Kelas : X SMA
Bab : Trigonometri

Pembahasan :
Cos L = (KL² + LM² - KM²)/(2KL.LM)
Cos L = (15² + 13² - 8²)/2(15)(13)
Cos L = (225 + 169 - 64)/390
Cos L = 330/390
Cos L = 33/39
Cos L = 11/13

Samping = 11
Miring = 13
Depan = √[13² - 11²] = 4√3

Maka Sin L = Depan/Miring
Sin L = 4/13 √3