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Home » Articles » LESSON NOTES (Mathematics) » Upper Primary


A RECTANGLE REC003ARTC

A RECTANGLE

The above shape is a shape of a rectangle.

It is named as rectangle ABCD

A rectangle is a four – sided flat shape. Every angle of a rectangle is a right angle (90°).

The following are the characteristics of the rectangle:

All interial angles are right angles (90°). Refer to the shape above.

Opposite sides are parallel ( from the shape above AB // CD and AC // BD)

Opposite  sides are equal  ( from the shape above AB = CD and AC = BD)

 

Perimeter of a rectangle

Finding the perimeter of a rectangle when the length and the width are given and finding the length or the width when the perimeter is given are the goals of this lesson

Given a rectangle with side length (L) and width (W), the perimeter (P) or distance around the outside of the rectangle can be found by doing

P = L + W + L + W = (2 × L) + (2 × W ) = (L + W) x 2

Example #1:
Find the perimeter of a rectangle when  L = 4 cm and W = 8 cm

solution
P = (2 × 4) + (2 × 8)  = (4 + 8) X 2
P = 12 x 2
P = 24 cm

Notice that it is perfectly ok to do P = 8 + 4 + 8 + 4 = 12 + 12 = 24
However, it is usually easier and quicker to multiply each dimension by 2 and adding the results.

Example #2:
Find the perimeter of a rectangle when  L = 9 cm and W = 11 cm.

solution
P = (L + W) x 2.
P = (9 + 11) x 2

P = 20 x 2
P = 40 cm


Example #3:
Find the perimeter of a rectangle with dimensions 2.4m by 1.3 m

solution
P = (L + W) x 2.
P = (2.4 + 1.3) x 2

P = 3.7 x 2
P = 7.4  cm

 

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Category: Upper Primary | Added by: Admin (07/Aug/2016) | Author: Yahya Mohamed E W
Views: 420 | Tags: WIDTH, voulume, Parallel, area, shapes, capacity, rectangle, Length, mathematics | Rating: 0.0/0
Total comments: 0
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