Question

The perimeter of a rectangle is about 13.9 cm. If you double the width of the rectangle the perimeter is about 17.8 cm. Find the dimensions of the smaller rectangle.

Answer 1

5cm by 1.95cm

Explanation:

Let the length of the rectangle be x

Let the width be y

Perimeter of a rectangle = 2x + 2y

If the initial perimeter of a rectangle is about 13.9 cm, then;

13.9 = 2x + 2y ..... 1

If when the width is double the perimeter is 17.8cm, then;

17.8 = 2x + 4y ..... 2

Subtract 1 from 2;

13.9 - 17.8 = 2y - 4y

- 3.9 = -2y

y = 3.9/2

y = 1.95 cm

Substitute y = 1.95 into 1 to get x;

From 1;

13.9 = 2x + 2y

13.9 = 2x + 2(1.95)

13.9 = 2x + 3.9

2x = 13.9-3.9

2x = 10

x = 5 cm

Hence the dimension of the smaller triangle is 5cm by 1.95cm