Write the maximum and minimum values of cos (cos x).
Let cos x = t
Range of t =(-1,1)
∴ Maximum and Minimum value of cos x is 1 and -1 respectively.
Now,
cos(-x) = cos x
∴ Range of cos(cos x) = [cos(1),cos(0)]
⇒ cos(cos x) = [cos1,0]