Question

Question #9c430

Answer 1

`a_n = pi(2n - 1)`

Explanation:

To find x-intercepts, `f(x) = 0`.

`cos(1/2x) = 0`

`x = 2cos^-1(0) = pi, 3pi, 5pi,...`

`a_n = pi(1 + 2(n - 1))`

`a_n = pi(2n -1)`