Perimeter & Area Review
What is Area?
What is Perimeter?
Area is the size of a surface!
Perimeter is the distance around a shape!
Example:
These shapes all have the same area of 9.
They do NOT have the same perimeter.
Perimeter=20
Perimeter= 12
Perimeter = 14
Area of Simple Shapes
Perimeter of Simple Shapes
Example: What is the area of this rectangle?
Example: What is the perimeter of this
rectangle?
To find the area of a rectangle or square:
Area = length x width or A= l x w
To find the perimeter you add the lengths of
the edges.
So we know w = 5 cm and l = 3 cm.
We know the opposite sides have the same
measurement so two sides are 3 cm and two
sides are 5 cm.
So:
So:
Area = 5 × 3 = 15cm2
Perimeter = 5 + 5 + 3 + 3 =16cm
The width is 5 cm, and the length is 3 cm,
Perimeter & Area Review
Perimeter & Area of Difficult Shapes
To help you understand an area, imagine painting it and how much paint you might use.
You can sometimes break a shape up into two or more simpler shapes:
Example: What is the area of this Shape?
Example: What is the perimeter of this shape?
20m
There are six sides you must add together. Two sides
are not labeled.
20m

5m
M
15m
N


You can figure out the length of side M by
adding 15m and 20m (to get 30m).
You can find the length of side N by adding
20m and 5m (to get 25m).
Now add all the side up.
(20+20+5+15+25+35=120)
The Perimeter is 120m.
Let's break the area into two parts:
Part A is a square:
Area of A = a2 = 20m × 20m = 400m2
Part B is a rectangle. It has a width of 15m and a length of 25m.
Area of B = 15x25=375m2
So the total area is: 775m2
Area = Area of A + Area of B = 400m2 + 375m2 = 775m2