Area of a Circle and its formula

Formula for Area of circle:

The formula to find a circle's area : π×(radius)² usually expressed as Πr² where r is the radius of a circle.

In the picture on the left, the area of the circle is the part of the circle that is changing color.

Example of Circle's Area

Since the radius of the circle on the left is 9", the area is Π(9")² = 81Π square inches ≈254 square inches
The area of the circle is the entire pink region.

Practice Problems
Problem 1)

What is the area of the circle on the left?
  Answer  
Remember the Formula:
A= Π×radius²
A = (22')² ×Π = 484Π square feet ≈ 1,520 square feet

Problem 2

What is this circle's area?
  Answer  
Remember the Formula:
A= Π×radius²
A = (5")² • Π = 25Π square inches ≈ 79 square inches

Problem 3
What is the area of a circle with a radius of 7 centimeters?
  Answer  
A = Π(7 centimeters)² = 49 Π centimeters squared ≈ 153 square centimeters

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