Interesting isn't it that when we realign the segments we end up with a parallelogram shape. Which is great, because it means we know how to find the area based on our knowledge that the area of a parallelogram has formula $A=bh$A=bh. In a circle, the base is half the circumference and the height is the radius.

Area of a Circle

$\text{Area of a circle}=\pi r^2$Area of a circle=πr2

Practice questions

QUESTION 1

Find the area of the circle shown, correct to one decimal place.

QUESTION 2

If the diameter of the circle is $24$24 cm, find its area correct to one decimal place.

QUESTION 3

If the radius of the circle is $9$9 cm, find its area correct to two decimal places.

Outcomes

7.G.B.4

Understand and use the formulas for the area and circumference of a circle to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.