Tg∝ = 3/4 cos²∝ – sin²∝ = …

Tan a = 3/4
maka cos a = 4/5
sin a = 3/ 5
cos² a – sin² a =
(4/5)²-(3/5)²
= 16/25 – 9/25 = 7/25
jadu hasil dari cos² a – sin² a = 7/25