Jika cos x = 3/5, maka tan 2x adalah

cosx = 3/5 maka sinx = 4/5
tan2x = sin2x/cos2x = 2sinxcosx/(1-2sin"x) = 2(4/5)(3/5)/(1-(4/5)") = (24/25)/(1-16/25)
= (24/25)/(9/25) = 24/25 . 25/9 = 24/9 = 8/3