Key Terms
Definition of Radius?
Radius is line from the centre to the circle.
What does Pi mean?
Pi means 3.14.
The area of a coin is 3.14 square centimeters. What is the radius?
1 cm
If the diameter of a water bottle is 12 in, then what is the circumference?
37.68
Definition of Diameter?
The Distance across the circle through the center.
What is the formula for circumference of a circle?
C=2pir or C=pi x d
The lens of a telescope has a diameter of 2 inches. What is the lens area? (Use 3.14 for 𝜋.)
3.14
If the radius of a circle is 10cm, then what is the circumference?
62.8
Definition of Radius
The Distance from the center to the circle.
If the diameter of a circle is 120cm, then what is the radius?
60cm
The radius of a bicycle tire is 4 feet. What is the area?
50.24 ft2
The diameter of a nickel is 2 cm. What is the circumference?
6.28 cm
What is a definition of a cord?
What is the full circle called?
Circumference.
The diameter of a circle is 12 in. What is the area?
113.04 in2
The diameter of your bicycle wheel is 25 in. How far will you move in one turn of your wheel?
78.5 in
What material do you use to create a circle?
A compass
Name all five of the types of circles that we have learned?
Radius, Diameter, Circumference, Area and Cord.
The radius of a circle is 9 cm. What is the area?
254.34 cm2
The radius of a circular rug is 4ft. What is the Circumference?
25.12ft