If sinθ = 4/5 then find cosθ.

We know,

sinθ = Opposite side/Hypotenuse

Given:

sinθ = 4/5

Opposite side = 4

Hypotenuse = 5

By Pythagoras Theorem

Hypotenuse² = Opposite side² + Adjacent²

Adjacent² = Hypotenuse² - Opposite side²

= 5² - 4²

= 25 – 16

= 9

Adjacent² = 9

Adjacent side= 3

cosθ = Adjacent side/Hypotenuse

= 3/5