cos (a-b) = 3/5 dan cos a x cos b= 7/5 tentukan nilai tang a x tang b

cos (a - b) = 3/5
cos a cos b + sin a sin b = 3/5
7/5 + sin a sin b = 3/5
sin a sin b = 3/5 - 7/5 = -4/5

tan a tan b
= sin a sin b / cos a cos b
= (-4/5) / (7/5)
= -4/5 × 5/7
= -4/7