a dan b sudut lancip. sin a = 4/5 dan sin b = 12/13 maka sin (a+b)

jawab

A dan B lancip

sin A = 4/5
triple  3,4,5
cos A = 3/5

sin B = 12/13
triple 5.12,13
cos B = 5/13

sin (A+ B) = sin A cos B + cos A sin B
= (4/5)(5/13) + (3/5)(12/13)
= 20/65 + 36/65
= 56/65