Use pi, π = 3.1 for all of the questions in this exercise.
1. For the circle shown below, where O is the centre, name:
a. Three radii
b. A diameter
2. What is the diameter of the following circles?
a. 
b. 
3. What is the radius of the following circles?
a. 
b. 
4. Complete the table below for these common circular objects (measured to 1 decimal place) :
Object

Circumference

Diameter

Circumference ÷ diameter


a  Soccer ball 
21.4 cm

6.8 cm


b  Can lid 
6.2 cm

2 cm


c  Two dollar coin 
24 mm

7.7 mm


d  Mars 
21310 km

6790 km


e  Clock 
54.7 cm

17.4 cm

What name is given to this ratio?
5. Find the circumferences and areas of the following circles.
a

b

6.
a. The radius of a circular desk is 1.3 metres, what is its diameter?
b. Find the area of a circle with a diameter of 10 centimetres.
c. What is the radius of a circle with a circumference of 34.2 cm?
d. What is the diameter of a circle with an area of 49.6 cm^{2}?
7. Find the area that is shaded red.
8. Find the volumes of the following solids:
a. A cylinder with a circular base of radius 5 centimetres and a height of 10 centimetres.
b. A sphere with a radius of 6 centimetres.
c. A cone with a base of 5 cm and a height of 10 cm.