circumference question

Question

A circle has a circumference of 100ft. How much does the radius increase if one foot is added to the circumference? use 6.28 for 2r

Answer 1

The formula for the circumference of a circle is:

 

      C = 2*pi*r

 

Where:

• C = the circumference
• pi = 3.14
• r = the radius of the circle

 

Solve for r:

 

      C = 2*pi*r

      C/2pi = r

 

For C = 100 ft:

 

      100/6.28 = r

      15.92 ft = r

 

Add one foot to the circumference = 100 ft + 1 ft = 101 ft:

 

      101/6.28 = r

      16.08 ft = r

 

The radius increases 16.08 - 15.92 = 0.16 ft