PERIMETER

Definition•Add up all sides of the object

25

P = 2 + 2 + 5 + 5

P = 14

Example

3cm

6cm

5cm

3+6+5 P = 14

5cm

2cm

2cm

5cm

2+2+5+5 P = 14

Now…You!!

Area of rectangles

Area is the space inside a

2D shape.

How do we calculate area?

• Measure the length.• Measure the width.• Multiply the length X width to calculate

the area!

But what if you want to calculate the area of an

irregular shape?• What if the shape has more than 4 sides?

• How can you do?

Length X Width

when there isn’t a length and there isn’t a width?

YOU HAVE TO MAKE RECTANGLES!

• Look at this shape. How could you calculate the area?

10cm

6cm6cm

4cm

You have to create more than one rectangle.

• Like this!

10cm

6cm

6cm

4cm

4cm

A = 6cm X 4cm = 24cm2

B = 6cm X 4cm = 24cm2

A + B = Area

24cm2 + 24cm2 = 48cm2

A

B

So to calculate the area of an irregular shape

•Split the shape into at least two rectangles.

•Calculate the area of each one.

•Add the two together.•You’re done!

Area of Squares

Side 3cm

3cm. Side

A square has all sides the same length.

Therefore, we do not need a length and a width. We can simply call them sides.

The area of a square can be calculated by multiplying side by side…

or side squared.

Area of a square is given by:

A = a 2

• where a = length of side

Great job!