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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$$ \pi \cdot$$(radius)2 usually expressed as $$ \pi \cdot r^2 $$ where r is the radius of a circle.
The area of a circle is all the space inside a circle's circumference.
play pause
area of circle demo


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


applet
Explore and discover the relationship bet wen the area formula , the radius of a circle and its graph with with our interactive applet
Practice Problems

Problem 1) Circle's Area

What is the area of the circle on the left?
Round your answer to the nearest tenth.
Answer


Problem 2
Area of Circle Two
What is this circle's area?
Round your answer to the nearest tenth.
Answer


Problem 3
What is the area of a circle with a radius of 7 centimeters?
Round your answer to the nearest hundredth
Answer


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)
Answer


Problem 5
What is the diameter of a circle if its area is 360 in2? (Round your answer to the nearest hundredth of an inch)
Answer
challenge problems

Challenge Problems

Problem 6

A circle has a diameter of 12 inches. What is its area in terms of $$\pi$$ . (Need a hint)
Answer


Problem 7

If a circle's radius is doubled, then how much did its area increase?
Answer
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Circles