Area and Circumference of a Circle

1
Area and Circumference of a Circle
2
The circle has a diameter of 12 cm. Calculate a.
The circumference b. The area
12 cm
a. Circumference ?d C 3.14 x 12 C 37.68 cm
b. Area ?r2 A 3.14 x 6 x 6 A
113.04 cm2
3
A circular pond has a diameter of 5 metres and a
1 meter wide path runs all the way around its
edge. Calculate the area of the path.
5 m
b. Area ?(R r)(R r) A 3.14(3.5
2.5)(3.5 2.5) A 3.14 x 6 x 1
A 18.84 m2
4
B
The circle has a diameter of 12 cm
720

• a. Calculate the arc length AB to 1 d.p
• Calculate the area of the sector AOB to 1 d.p.

A
O

• Arc AB (72 360) x (?d)
• AB 0.2 x 3.14 x 12
• AB 7.5 cm
• b. Area sector AOB (72 360) x (?r2)
• AOB 0.2 x 3.14 x 62
• AOB 22.6 cm2