What equation represents the function on the graph

cos 4x

Step-by-step explanation:

Because this graph begins at (0, 1), we immediately suspect that it's a cosine function.  Additionally, since there are 4 cycles of this cosine function between x = 0 and x = 2pi, we suspect horizontal compression:

cos 4x

i think it is c, not positive though

step-by-step explanation:

56.6

step-by-step explanation:

the ratio of the perimeters is equal to the scale.

the ratio of the areas is equal to the square of the scale.

34 / 20 = k

a / 19.6 = k²

substituting:

a / 19.6 = (34 / 20)²

a = 19.6 (34 / 20)²

a ≈ 56.6