Maths Question

Question

Which is the best estimate of the circumference of a circle whose area is 113.04 square feet.

 

1.   6 feet

 

2.  12 feet

 

3.   37.69 feet

 

4.   18.84  feet.

Answer 1

the area of a circle is

A = pi * r^2, meaning that

r = sqrt(A/pi)

for this scenario that gives a value of "r" of

r = sqrt(113.04/3.14) = 6

from there then you can find the circumference by taking

C = 2*pi*r = 2*pi*(6) = 12pi = 37.68 feet

Answer 2

The area formula pi r², so pi r² = 113.04.  Divide 113.04 by 3.14, and you get r² = 36.  Take the square root of 36 to find the radius.

 

Now, plug the 6 into the circumference formula, C = 2 pi r, so 2 times 3.14 times 6 equals 37.68.  The best estimate is 3.  37.69.