Question

Write a cosine function for the graph.

http://schools.connectionsacademy.com/content/media/102877-5272010-92002-PM-1855950374/res00000/ppg/examview/images/mc012-1.jpg

Answer 1

Well, cosine goes through the point (0,1). This one doesn't. So it is shifted. It is shifted DOWN two and to the right (what looks like) 2pi/3. And also has an amplitude of 2. So you would have:
f(x)=2cos(x+(2pi/3))-2

Answer 2

Actually, it should read: f(x)=2cos(x-(2pi/3))-2

Answer 3

The 2 stretches it. The -2pi/3 shifts it to the RIGHT. And the -2 shifts it DOWN.

Answer 4

Just for clarity, the 2 stretches it VERTICALLY.