1. Easy period questions

Well basically I have to determine the equation of the graph. The answer is y=2cos2x. I was just wondering how you got the period from looking at the graph. The 4 points on the x-axis is pi/2, pi, 3pi/2, and 2pi.

Thanks a lot for helping!

2. Originally Posted by Thatoneguy12345
Well basically I have to determine the equation of the graph. The answer is y=2cos2x. I was just wondering how you got the period from looking at the graph. The 4 points on the x-axis is pi/2, pi, 3pi/2, and 2pi.

Thanks a lot for helping!
best way is by looking at the horizontal distance from "peak" to "peak" or "trough" to "trough"

or, you can calculate it. for sine or cosine functions of the form

$y = A\cos(Bx)$

period, $T = \frac{2\pi}{|B|}$