Everything Maths Grade 11

16.2 CHAPTER 16. GEOMETRY

Step 2 : Substitute the given values

=

1

3

. 2. 2. 3

=

1

3

. 12

= 4 cm^3

We accept the followingformulae for volume andsurface area of a sphere(ball).

Surface area = 4πr^2

Volume =

4

3

πr^3

Exercise 16 - 1

1. Calculate the volumes and surface areas of the following solids: (Hint for (e): find the perpen-
   dicular height using Pythagoras).

�

�

�

�

4

6

7

14

3

5 13

24

24

a) b) c) d) e)

a sphere a hemisphere a cone a hemisphere on

top of a cone

a pyramid with

a square base

2. Water covers approximately 71% of the Earth’s surface. Taking the radius of the Earth to be 6378
   km, what is the total area of land (area not covered by water)?