Circle Basics
What is the name of the distance from the centre of a circle to the edge?
Radius
Find the area when r = 5 cm.
78.5 cm2
What fraction of a circle is a 90° central angle?
1/4
A circular table has a radius 4 m. Find the area.
50.24 m2
If r = 3, what is the diameter and area?
d = 6
A = 28.26
If the radius is 8 cm, what is the diameter?
16 cm
Find the area when the diameter is 12 m.
113.0 m2
What fraction of a circle is 180°?
1/2
A pizza has a diameter 20 cm. What is its area?
Two circles have a radii of 4 cm and 8 cm.
How many times larger is the bigger circle's area?
4 times larger
What is the sum of all central angles in a circle?
360°
Find the radius if the area is 50.24 cm2.
4 cm
Find the area of a 90° sector if r = 8 cm.
50.24 cm2
A circular garden has a radius 10 m. Grass costs $3 per m2.
How much would it cost to cover the garden?
$942
Find the central angle of a sector that is 1/5 of a circle.
72°
If the diameter is 14 m, what is the radius?
7 m
The radius doubles. What happens to the area?
Area becomes 4 times larger
(b/c r2)
Find the area of a 120° sector if r = 6 cm.
37.68 cm2
A circular rug covers 78.5 m2. What is its radius?
5 m
A 72° sector has area 31.4 cm2.
What is the total area of the circle?
157 cm2
A circle has a radius of r. Write a formula for its area.
A = πr2
Find the area when r = 7 cm.
153.9 cm2
A circle is divided into sectors of 100°, 140°, and 120°.
Prove they form a complete circle.
100 + 140 + 120 = 360°
A pizza with a diameter of 30 cm is cut into 6 equal slices.
117.8 cm2
A circle has area 314 cm2.
It is divided into 4 equal sectors.
Find the radius.
10 cm