Cambridge International Mathematics

Mensuration (length and area) (Chapter 9) 203

Example 10 Self Tutor

Find a formula for the areaAof:

Area=area of rectangle+area of semi-circle

) A=2a£b+^12 £¼£a^2 fthe radius of the semi-circle isaunitsg

) A=

μ

2 ab+

¼a^2

2

¶

units^2

EXERCISE 9D

1 Calculate, correct to 3 significant figures, the circumference of a circle with:

a radius 8 cm b radius 0 : 54 m c diameter 11 cm.

2 Calculate, correct to 3 significant figures, the area of a circle with:

a radius 10 cm b radius 12 : 2 m c diameter 9 : 7 cm.

3 Calculate the length of the arc of a circle if:

a the radius is 12 : 5 cm and the angle at the centre is 60 o

b the radius is 8 : 4 m and the angle at the centre is 120 o.

4 Calculate the area of a sector of:

a radius 5 : 62 m and angle 80 o b radius 8 : 7 cm and angle 210 o.

5 Find the area shaded:

abc

de f

2 a

b

3m

7cm

12 m

4cm

120°

5m

36°

9.8 cm

6 Calculate the radius of a circle with:

a circumference 20 cm b area 20 cm^2 c area 9 ¼m^2.

IGCSE01

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Y:\HAESE\IGCSE01\IG01_09\203IGCSE01_09.CDR Thursday, 2 October 2008 11:52:51 AM PETER