diketahui : cos(a+b) 1/2 dan sin A sin B = 1/5 nilai tan A tan B =

Bab Trigonometri
Matematika SMA Kelas X

cos (a + b) = 1/2
cos a cos b - sin a sin b = 1/2
cos a cos b - 1/5 = 1/2
cos a cos b = 1/2 + 1/5
cos a cos b = 7/10

tan a tan b = (sin a sin b) / (cos a cos b)
                  = (1/5) / (7/10)
                  = 2/7