Imagine you are walking around a building, to know how far you have walked you will need to measure the distance around the building. That’s called perimeter!
The perimeter of an object is the distance around the object.
To calculate the perimeter of a shape, you need to add up all the sides of the shape.
Take a look at the rectangle below:
The perimeter of this rectangle is the sum of all the sides
= L + L + B + B or = 2L + 2B
= 10m + 10m + 7m + 7m = (2 x10m) + (2 x7m)
= 20m + 14m = 20m + 14m
= 34m = 34m
Let’s take a look at the square below and find the perimeter.
Remember, the perimeter of a shape is the sum of all the sides.
Since all the sides of a square is equal, the Perimeter of a square is
= L + L + L + L Or = 4L
= 6cm + 6cm + 6cm + 6cm = 4 x 6
= 12cm + 12cm = 24cm
= 24cm
Now that we have learned about the perimeter of shapes, can you take a look at the shape below and find the perimeter?
A. 20 cm
B. 21 cm
C. 23 cm
Brilliant! Option B is the correct answer.
Remember, the perimeter of a shape is the sum of all the sides.
P = a + b + c
P = 6cm + 7cm + 8cm
P = 13cm + 8cm
P= 21cm