Question

the function f(r) gives the area of a circle with radius r. it can be written in equation form as f(r) = 3.14r². what is f(3)?

a. 28.26
b. 18.84
c. 12.14
d. 88.74

Explanation:

Step1: Substitute \( r = 3 \) into the function

Given \( f(r)=3.14r^{2} \), when \( r = 3 \), we have \( f(3)=3.14\times3^{2} \).

Step2: Calculate \( 3^{2} \)

\( 3^{2}=3\times3 = 9 \). So \( f(3)=3.14\times9 \).

Step3: Calculate the product

\( 3.14\times9=(3 + 0.14)\times9=3\times9+0.14\times9=27+1.26 = 28.26 \).

Answer:

A. 28.26