Answer:
The range of the function y = 2cos x is -2 <y < 2 .
Explanation:
We know that cos (0) = 1 and cos (π) = - 1 are the two extreme values which cos x assume when x ∈ R and it is also that cos (x) is a continuous periodic function with period 2π when x ∈ R ,
since ,
cos (x + 2π) = cos x
So, the range of the function y = 2cos x is -2 <y < 2 .