Finding the circumference of the circle

Question

I hope I can get some help. a circle is 4.5 ft. what would be the circumference of the circle and then round it to the nearest hundredth?

Answer 1

Circumference = 2 Pi r

Circumference = Pi d

Pi is roughly 3.14159

r is the radius, the distance from the middle of the circle to the edge.

The diameter (d) of a circle is the distance across the circle, from edge to edge, going through the middle.

diameter = 2 * radius

d = 2 * r

Your question says "a circle is 4.5 ft" but it doesn't say if that 4.5 is the radius or diameter.

 

If the radius is 4.5 ft then

C = 2 * 3.14159 * 4.5

C = 28.27431

rounded to the hundredths place

C = 28.27 ft

 

If the diameter is 4.5 ft then

d = 4.5 = 2 * r

4.5 = 2 * r

r = 2.25

C = 2 Pi r

C = 2 * 3.14159 * 2.25

C = 14.137155

round to the hundredths place

C = 14.14