Question

Choose the function whose graph is given by:

A. y = cos(ix)

B. y = cos(2x)

C. y = cos(ix)

D. y = cos(4x)

Answer 1

Answer is B. y = cos (2x)

The reason for that is that the default f(x)=cos(x) function is 1 when x is 0, and is 0 when x is pi/2. The graph shown is also 1 when x is 0, but it is 1 when x is pi/4 instead, which means that the graph is 2 times faster than the default one. This is why the answer is y=cos2x
:)

Answer 2

y=cos(4x)

Explanation:

i just took the test ;p