Circumference and radius

Question

Kelsey bought a circular rug that is 8 feet in diameter. The rug has a blue border and a red circular center that is 6 feet in diameter. What is the area of the blue border?

Answer 1

I will outline the procedure to follow.

 

The area of a circle is calculated using the formula...

A=πr².......area of a circle,

d=2r.........diameter is 2 times the radius

 

Calculate the area of the larger circle (8ft diameter) and 

subtract the area of the smaller circle (6ft diameter).  The 

resulting value is the area of the blue border.  

 

Substitute the numerical values into the formulas for the

process described above and evaluate.

Answer 2

The blue area is the difference between the area of the 8 ft diameter rug and the area of the 6 ft diameter rug.

 

From each diameter, you can figure out the appropriate radius. Then find the area of the larger circle & subtract from that the area of the smaller circle, using the formula Area = pi•radius² for each circle.