Test Index

WAEC Mathematics 2010 Paper

© africaexams.com

Question : 19

Total: 49

What is the length of a rectangular garden whose perimeter is 32cm and area 39cm²?

25cm
18cm
13cm
9cm

Solution:

Concept:

Use the formulas for perimeter and area of a rectangle to find the dimensions.

Explanation:

Let the length be

l

and the breadth be

b

.

Perimeter

= 2(l+b) = 32

cm

So,

l+b = 16

cm and

b = 16-l

.

Area

= l \times b = 39

cm

^2

Substitute

b = 16-l

:

l(16-l) = 39

16l - l^2 = 39

l^2 - 16l + 39 = 0

Factorise:

(l-13)(l-3) = 0

So,

l = 13

cm or

l = 3

cm.

The length is the longer dimension, so

l = 13

cm.

Answer:

C. 13cm

© africaexams.com

Go to Question:

Prev Question

Next Question