tan x = 0,75 dan x di kuadran 1, maka nilai cos 2x = ???

tanx = 0,75 = 3/4

tanx = depan/samping
Depan = 3
Samping = 4
Miring = 5 (phytagoras)

cos 2x = cos²x - sin²x
= (sa/mi)² - (de/mi)²
= (4/5)² - (3/5)²
= 16/25 - 9/25
= 7/25