Cambridge International Mathematics

Mensuration (solids and containers) (Chapter 11) 237

Example 5 Self Tutor

Find the surface areas of the following solids:

a solid cylinder b

a Surface area

=2¼r^2 +2¼rh

=2£¼£ 62 +2£¼£ 6 £ 15

= 252¼

¼ 792 cm^2

b Surface area

=4¼r^2

=4£¼£ 82 cm^2

= 256¼cm^2

¼ 804 cm^2

Example 6 Self Tutor

Find the surface area of a solid cone of base radius 5 cm and height 12 cm.

Let the slant height belcm.

l^2 =5^2 +12^2 fPythagorasg

) l^2 = 169

) l=

p

169 = 13 fasl> 0 g

Now A=¼r^2 +¼rl

) A=¼£ 52 +¼£ 5 £ 13

) A=90¼

) A¼ 283

Thus the surface area is approximately 283 cm^2 :

EXERCISE 11A.2

1 Find the outer surface area of the following:

abc

de f

6cm

12 cm

can (no top)

3.8 m

3.8 m

tank (no top)

5.5 cm

2.3 cm

hollow throughout

8cm

3cm

solid

5cm

10 cm

solid

6cm

15 cm

2.2 m

solid

6.8 m

lcm

12 cm

5cm

8cm

IGCSE01

cyan magenta yellow black

(^05255075950525507595)
100 100
(^05255075950525507595)
100 100
Y:\HAESE\IGCSE01\IG01_11\237IGCSE01_11.CDR Wednesday, 29 October 2008 9:23:46 AM PETER