Question

Evaluate the following:

`cos^-1{cos  (13pi)/6}`

Answer 1

We know

`cos^-1(costheta)=thetaif 0<=theta<=pi`

We have

`cos^-1{cos  (13pi)/6}=cos^-1{cos(2pi+pi/6)}`

`= cos^-1{cos(pi/6)}`

`=pi/6`