Find equation from graph

[plain sinew]

someone please explain this to me ? 😦

[surreal pagoda]

Plug in test points x = 0, pi/2
, pi and check the values of the answer choices to see if they match the graph

[boreal pond]

I gotchu

[plain sinew]

And how do i check that?

[boreal pond]

There are a few critical points

Pi/2, pi, 3pi/2, 2pi are usually where they are

The functions aren’t manipulated period wise

[dusky plume]

we know cos(0) = 1, but in the graph it maps pi/2 to 1, hence if x is pi/2, to shift the graph such that y = 0, when x = pi/2, we simply start at pi/2, then subtract x = pi/2, therefore the answer is cos(pi/2 - x), you can use similar reasoning for other x points

[naive nexus]

bro is correct