Finding the Finding the Area of a Area of a RectangleRectangle

Area of a RectangleArea of a Rectangle

ObjectivesObjectives

• To calculate areas of To calculate areas of rectanglesrectangles

• To calculate areas of To calculate areas of polygons made of rectanglespolygons made of rectangles

Area of a RectangleArea of a Rectangle

Area is the measure of how much space Area is the measure of how much space a shape takes up. We measure it in a shape takes up. We measure it in

squares such as square centimetres or squares such as square centimetres or metres etc.metres etc.1 cm

1 cm

11 22 33 44 55 66 77

88 99 1010 1111 1212 1313 1414

1515 1616 1717 1818 1919 2020 2121

2222 2323 2424 2525 2626 2727 2828

This rectangle This rectangle takes up 28 takes up 28 squares. squares.

It has an area of It has an area of 28 square 28 square

centimetrescentimetres

28 cm28 cm22

Area of a RectangleArea of a Rectangle

It could take a long time to cover It could take a long time to cover shapes in squares. Luckily there is an shapes in squares. Luckily there is an

quicker way.quicker way.7 cm7 cm

4 cm4 cm

×× = = 28 cm28 cm22

Area of a RectangleArea of a Rectangle

Use this formulae to find the area of Use this formulae to find the area of rectangles.rectangles.

Area of a rectangle = length × breadthArea of a rectangle = length × breadth

lengthlength

breadthbreadth

Area of a RectangleArea of a Rectangle

Can you find the areas of these Can you find the areas of these rectangles?rectangles?

5 cm5 cm

3 cm3 cm15 cm15 cm22

2 cm2 cm

7 cm7 cm

14 cm14 cm22

7 m7 m

7 m7 m49 m49 m22

Area of a RectangleArea of a Rectangle

Can you think of a way to find the Can you think of a way to find the area of this shape?area of this shape?

12 cm12 cm

6 cm6 cm

5 cm5 cm

7 cm7 cm

3 cm3 cm

Area of a RectangleArea of a Rectangle

Split the shape into rectangles?Split the shape into rectangles?

12 cm12 cm

6 cm6 cm

5 cm5 cm

7 cm7 cm

3 cm3 cm

Area of a RectangleArea of a Rectangle

Find the area of each rectangle?Find the area of each rectangle?

6 cm6 cm

5 cm5 cm

7 cm7 cm

3 cm3 cm

5 × 6 = 30 cm5 × 6 = 30 cm22

7 × 3 = 21 cm7 × 3 = 21 cm22

Area of a RectangleArea of a Rectangle

Add the areas together to find the area Add the areas together to find the area of the complete shape?of the complete shape?

30 + 21 = 51 cm30 + 21 = 51 cm22

30 cm30 cm22

21 cm21 cm22

Area of a RectangleArea of a Rectangle

Can you find the areas of these shapes?Can you find the areas of these shapes?

11 cm11 cm

5 cm5 cm

7 cm7 cm

4 cm4 cm

2 cm2 cm

43 cm43 cm22

6 m6 m

4 m4 m

3 m3 m

4 m4 m

1 m1 m

22 m22 m22

Area of a RectangleArea of a Rectangle

Here is a challenge can you work out Here is a challenge can you work out the area of this shape with a hole in it?the area of this shape with a hole in it?

10 cm10 cm

5 cm5 cm

5 cm5 cm

2 cm2 cm

Clue: Take the area of the hole from the area of the Clue: Take the area of the hole from the area of the whole!whole!

50 cm50 cm2 2 – 10 cm– 10 cm22 = 40 cm = 40 cm22

Remember:Remember:

Area of a rectangle = length × breadthArea of a rectangle = length × breadthlengthlength

breadthbreadth

Split more complicated shapes into Split more complicated shapes into rectangles and find the area of each rectangles and find the area of each rectangle then add them together.rectangle then add them together.

Over to you.Over to you.