Diketahui a=6 b=6 c=6√2 Ditanya cos c?

Kelas 11 Matematika
Bab Trigonometri Lanjut

cos C = (a² + b² - c²)/(2 . a . b)
cos C = (6² + 6² - (6√2)²)/(2 . 6 . 6)
cos C = (36 + 36 - 72)/72
cos C = 0