Question

Jika sin a = 4/5, dan sin B = 7/25 ( a dan B sudut lancip ), trntukan bahwa sin (a-B) = 3/5 ?

Answer 1

Sin a = 4/5 = de/mi => sa = √(5^2 - 4^2) = √9 = 3
cos a = sa/mi = 3/5

sin b = 7/25 = de/mi => sa = √(25^2 - 7^2) = √576 = 24
cos b = sa/mi = 24/25

sin (a - b)
= sin a cos b - cos a sin b
= 4/5 . 24/25 - 3/5 . 7/25
= 96/125 - 21/125
= 75/125
= 3/5