F is a trigonometric function of the form f(x) = a cos( bx + c) + d

The function is f(x) = 3cos(2πx)—6 if the function has a maximum
point at (-2, -3) and a minimum point at (–2.5, -9).
What is trigonometry?
Trigonometry is a branch of mathematics that deals with the relationship between sides and angles of a right-angle triangle.
We have a function:
f(x) = a cos(bx + c) + d
Here a is the amplitude:
Midline line y = -6
a = |-6-(-3)| = 3
d = -6 (midline)
Difference = |-3 + 2| = 1
b = 2π/1 = 2π
By plugging points in the equation, we get
c = 0
The equation become:

Thus, the function is f(x) = 3cos(2πx)—6 if the function has a maximum
point at (-2, -3) and a minimum point at (–2.5, -9).

Do you have answers choice but i think the answer is 18 because 2/3 times 18 =12 serving hope this can i have brinlyest