diiketahui:sin A =6/10 sin B = 15/25 jika A-B merupakan sudut lancip hitunglah cos (A-B)

sinA = 6/10 = 3/5
cosA = 4/5

sinB = 15/25 = 3/5
cosB = 4/5

cos(A - B)=cosA cosB+sinA sinB=(4/5)(4/5)+(3/5)(3/5)=16/25+9/25=25/25 = 1