whongaliem AB / sin C = AC / sin B 10 / sin C = 15 / sin 30° 10 / sin C = 15 / (1/2) 15.sin C = 1/2 . 10 15.sin C = 5 sin C = 5/15 sin C = 1/3
sin² C + cos² C = 1 (1/3)² + cos² C = 1 1/9 + cos² C = 1 cos² C = 1 - 1/9 cos² C = 8/9 cos C = √(8/9) = (1/3)√8 = (1/3).2√2 = (2/3)√2 ..... jawaban : e
10 / sin C = 15 / sin 30°
10 / sin C = 15 / (1/2)
15.sin C = 1/2 . 10
15.sin C = 5
sin C = 5/15
sin C = 1/3
sin² C + cos² C = 1
(1/3)² + cos² C = 1
1/9 + cos² C = 1
cos² C = 1 - 1/9
cos² C = 8/9
cos C = √(8/9)
= (1/3)√8
= (1/3).2√2
= (2/3)√2 ..... jawaban : e