Question

Evaluate:

`cos[tan^-1 (3/4)]`

Answer 1

Let `tan^-1 (3/4) = theta`

`3/4` = tan θ

tan θ = `3/4`

∴ cos θ = `4/5`

`[because theta = tan^-1  3/4]`

Now `cos[tan^-1 (3/4)] = cos theta = 4/5`