The range of f(x)=cos(x)+sin(x)f(x) = \cos(x) + \sin(x)f(x)=cos(x)+sin(x) is:
[−2,2][-2, 2][−2,2]
[0,2][0, \sqrt{2}][0,2]
[−2,2][-\sqrt{2}, \sqrt{2}][−2,2]
[−1,1][-1, 1][−1,1]