Find the values of each of the expression

is equal to

(Forcos^-1(cosx) type of problem we have to always check whether the angle is in the principal range or not. This angle must be in the principal range.)

So here,

Now, can be written as,

where [since, cos(π + x) = -cosx]

as cos^-1(-x) = π – cos^-1

Hence,