For f(x) = e^cos(x) use your graphing calculator to find the number of zeros for f '(x) on the closed interval [0, 2π].

Question

A 1
B 2
C 3
D 4

Answer 1

f'(x) = -sinx e^cosx

since e^cosx is never zero, f' has zeroes where sinx has zeros.

I'm sure you remember enough trig to figure that out.