Question

I need help can’t work out the right answer. What is the equation of the sinusoid shown in graph?

Answer 1

`C)y=2cos\left(3x\right)`

1) The general form of a cosine function is:

`y=acos\left(b\left(x-h\right)\right)+k`

2) Let's pick from the graph, the amplitude, the period, the horizontal and the vertical shift.

We can tell that half of the distance between the maximum point and the minimum point is 2

Let's find the period

`P=(2\pi)/((2\pi)/(3))=2\pi *(3)/(2\pi)=3`

3) Let's resort to the picture. The only cosine function that has an amplitude of 2 and a period of 3 is C and y=2cos(3x) has a vertical shift =0