Date:30/04/2020

Class: JSS 1

Subject: Mathematics

Topic: Plane Shape

Plane Shape

Plane shape are shapes with two dimensions. They are formed by intersection of horizontal and vertical lines. Examples are  rectangle, square, parallelogram, trapezium, rhombus and so on.

Using formulae to calculate  perimeters

Rectangle

Perimeter of rectangle =2 (L+b)

P=2(L+b)

Where p is the perimeter,

L is the length and b is the breadth

To calculate length

Length of rectangle = ^p_{/ 2} – breadth

To calculate breadth

Breadth of rectangle  = ^p_{/ 2} – length

Example 1: A rectangular piece  of land measure  57m by 42m. What is the perimeter of the field

Solution

P=2(L+b)

P=2(57m +42m)

P=2(99m)

P=2 x99m =198m

Example 2:A rectangle has a perimeter of 52cm. calculate the breadth, if the length is 14cm

Breadth = ^p_{/ 2} – length

b = 52cm / 2- 14cm

b = 26cm – 14cm =12cm

Assignment

1. A rectangle has a perimeter of 60m. Find the length of the rectangle if its breadth is (a)10m (b)5m