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# Area of a Circle and its formula

## Practice Problems & examples

### 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.
The area of a circle is all the space inside a circle's circumference.
 In the picture on the left, the area of the circle is the part of the circle that is changing color.

## Interactive Area of a Circle

Explore and discover the relationship between area, radius and graph of a circle. . Just click and drag the points.
$$Area = \pi \cdot radius^2$$


Practice Problems

Problem 1)

What is the area of the circle on the left?

Problem 2

What is this circle's area?

Problem 3
What is the area of a circle with a radius of 7 centimeters?

Problem 4
What is the radius of a circle if its area is 120 in2? (Round your answer to the nearest hundredth of an inch)

Challenge Problems

Problem 5

A circle has a diameter of 12 inches. Calculate its area. (Need a hint)