Perimeter. 

Perimeter is the distance around a two-dimensional shape

Formulas for finding perimeter of regular objects

Perimeter of a rectangle = 2l + 2w =2(l + w) (where l = length, w= width)

Perimeter of a squire = 4l (l = size of one side)

Circumference of a circle = 2πr = 2πd (where r = radius, d = diameter, d = 2r)

 

Example 1

Ishaka has a plot of land with measurements as shown below

What is the distance around Ishaka’s plot?

Distance around the plot              = sum of all sides = 30 + 55 + 50 + 60 = 195cm

 

Example 2

Juma has a piece of land (plot) with measurements as shown in the figure below. He would like to put a line of fencing wire around the piece of land. What is the minimum length (in metres) of facing wire he would require?

DC2 = BD2 + BC2 =402 + 302 = 1600 + 900 DC2 = 2500 DC = √2500 =50 Perimeter = AB + CD + DE + EA = 70+50+40+40 =200m Hence the length of the wire required = 200m

 

For revision questions download PDF

Perimeter- upper primary

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