Question

The range of the function y = 2cos x is -2 ≤ y ≤ 2.

Answer 1

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 .