Question

y = cos x is increasing on the interval __________________ .
a. (pi, 2pi)
b. (-pi, pi)
c. (0, 2pi)
d. (0, pi)
e. (-pi/2, pi/2)
First of all, is this question asking when the wave of a cosine function is increasing, as in going up? or is it asking when it repeats? Because im stuck between choice a and choice c

Answer 1

going up

Answer 2

it should be (pi,2pi)