Question

Evaluate the following:

`cot^-1(cot  (9pi)/4)`

Answer 1

We know that

cot^-1 (cot θ) = θ,   (0, π)

We have

`cot^-1(cot  (9pi)/4)=cot^-1[cot(2pi+pi/4)]`

`=cot^-1(cot  pi/4)`

`=pi/4`