Radius & Diameter
Circumference
Area
Working Backwards
Vocabulary
100
What is Radius?
Radius is the distance from the centre of a circle to any point of the circle.
100
What is Circumference?
Circumference is the distance around a circle.
100
What is the formula for area of a circle?
A= pi*r2
100
A bicycle wheel has a radius of 1 foot. If the bicycle wheel rotates one time, what distance is travelled?
2pi or 6.28 feet.
100
Two radii that meet at the center of a circle at 180
diameter
200
What is Diameter?
The distance across a circle measured through its centre.
200
A circle has a diameter of 3 inches. This is the circumference.
9.42
200
A circle has a diameter of 16. Find the area.
200.96
200
The circumference of a wheel is 113.04 inches. What is the radius of the wheel?
18 inches
200
Two chords that form an angle in a circle.
inscribed angle
300
The diameter is 10 meters. Find the radius.
the radius is 5 meters
300
A circle has a radius of 51.19 inches. What is the circumference?
321.47 inches
300
A circle has a radius of 50 miles. What is the area of the circle TO THE NEAREST MILE?
7854 mi2.
300
If your circumference is 72.98 what is your radius?
11.62
300
Two radii that meet at less than 180 degrees in a circle.
central angle
400
The Diameter is 25 meters. What is the Radius?
The Radius is 12.5 meters.
400
Circumference 
18.8
400
A pizza is 16 inches long (diameter). It is cut into 4 pieces. Jane eats 3 of the pieces. What is the area of pizza she is eating?
What is 48 pi in2
400
John owns a circular pool in his back yard. If he swims around the pool, he swims 30pi meters. What is the radius of this circle?
15 meters
400
An arc whose endpoints touch the diameter.
semi-circle
500
The Radius is 81 cm. What is the Diameter?
the Diameter is 162 cm.
500
Circumference 
25.1
500
Find the area 
254.5
500
A circle has a circumference of
6pi
.
What is the area?
28.26
500
The central angle divided by 360, and multiplied by pi*r2
Area of a Sector