Area of a Circle
We already know that area is the space inside a 2D shape. We can find the area of a circle, but we will need a special rule.
The following investigation will demonstrate what happens when we unravel segments of a circle.
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.
$\text{Area of a circle}=\pi r^2$Area of a circle=πr2
Worked Examples
QUESTION 1
If the radius of the circle is $5$5 cm, find its area.
Give your answer as an exact value.
QUESTION 2
Find the area of the shaded region in the following figure, correct to one decimal place.
QUESTION 3
Find the area of the shaded region in the following figure, correct to one decimal place.
