Question

Determine which function is represented by the graph. Do not use a calculator. (a) f ( x ) = 4 cos ( x + π ) (b) f ( x ) = 4 cos 4 x (c) f ( x ) = 4 sin ( x − π ) (d) f ( x ) = − 4 cos ( x + π ) (e) f ( x ) = 1 − sin x 2

Answer 1

The graph of the function appears to be a cosine function that has been shifted to the left by π/2 units, and has an amplitude of 4.

Option (a) is a cosine function that has been shifted to the left by π units, but does not have the amplitude of 4.

Option (b) is a cosine function that has a period of π/2, which is much shorter than the period of the graph.

Option (c) is a sine function that has been shifted to the right by π units, but does not have the amplitude of 4.

Option (d) is a cosine function that has been shifted to the left by π units and has the correct amplitude of 4.

Option (e) is not a cosine or sine function, so it cannot be the correct answer.

Therefore, the function represented by the graph is:

f(x) = -4 cos(x + π)

which is Option (d).

Explanation: