bila sin A = 5/ 13 dan tan b= 4/3 dengan A sudut tumpul dan B sudut lancip, maka sin (A-B)

sin A = 5/13 = y/r 
triple x,y,r = 12,5, 13
cos A = x/r = 12/13

tan B = 4/3 = y/x
triple  x,y,r = 3,4,5
sin B = y/r = 4/5
cos B = x/r = 3/5


sin ( A - B ) = sin A cos B - cos A sin B
= (5/13)(3/5) - (12/13)(4/5)
= 15/65 - 48/65
= -33/65