To determine which equation is the formula for finding the area of a circle using 3.14 for π, let's review the formula for the area of a circle.
The area [tex]\( A \)[/tex] of a circle with radius [tex]\( r \)[/tex] is given by the equation:
[tex]\[ A = \pi r^2 \][/tex]
Since the problem specifies using 3.14 for π, we replace π with 3.14 in the formula:
[tex]\[ A = 3.14 \times r^2 \][/tex]
Now, let’s examine each choice:
A. [tex]\( A = 3.14 d^2 \)[/tex]
This formula is incorrect because it uses the diameter [tex]\( d \)[/tex] squared instead of the radius [tex]\( r \)[/tex] squared. The proper formula uses the radius.
B. [tex]\( A = 3.14 \times d \)[/tex]
This formula is incorrect because it multiplies π by the diameter instead of involving the radius squared.
C. [tex]\( A = 3.14 \times r^2 \)[/tex]
This formula is correct because it matches the area formula where we multiply 3.14 (π) by the radius squared.
D. [tex]\( A=3 \cdot 14 + r + 2 \)[/tex]
This formula is incorrect and does not resemble the area formula of a circle.
Therefore, the correct choice is:
[tex]\[ \boxed{3} \][/tex] which corresponds to:
C. [tex]\( A = 3.14 \times r^2 \)[/tex]
