Dik: sin A= 6/10 , cos B= 12/13 A dan B lancip Hitunglah: a. Sin (A+B) b. Cos (A-B)

Fungsi trigonometri

sin A = 6/10 = 3/5 --> triple = 3,4 5
cos A = 4/5

cos B = 12/13 --> triple = 5,12,13
sin B  = 5/13

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

b. cos (A-B)= cos A cos B + sin A sin B
cos (A- B) = (4/5)(12/13) + (3/5)(5/13)
cos(A-B) = (48+ 15)/(65) = 63/65