Finding the Area of a Rectangle

Objectives To calculate areas of rectangles To calculate areas of polygons made of rectangles

Area is the measure of how much space a shape takes up Area is the measure of how much space a shape takes up. We measure it in squares such as square centimetres or metres etc. 1 cm This rectangle takes up 28 squares. It has an area of 28 square centimetres 28 cm2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

It could take a long time to cover shapes in squares It could take a long time to cover shapes in squares. Luckily there is an quicker way. 7 cm 4 cm × = 28 cm2

Area of a rectangle = length × breadth Use this formulae to find the area of rectangles. length breadth Area of a rectangle = length × breadth

Can you find the areas of these rectangles? 5 cm 3 cm 2 cm 7 cm 15 cm2 14 cm2 7 m 49 m2

Can you think of a way to find the area of this shape? 5 cm 6 cm 7 cm 3 cm 12 cm

Split the shape into rectangles? 5 cm 6 cm 7 cm 3 cm 12 cm

Find the area of each rectangle? 5 cm 5 × 6 = 30 cm2 7 × 3 = 21 cm2 6 cm 7 cm 3 cm

Add the areas together to find the area of the complete shape? 30 + 21 = 51 cm2 30 cm2 21 cm2

Can you find the areas of these shapes? 11 cm 5 cm 7 cm 4 cm 2 cm 6 m 22 m2 3 m 4 m 43 cm2 1 m 4 m

Clue: Take the area of the hole from the area of the whole! Here is a challenge can you work out the area of this shape with a hole in it? 2 cm 5 cm 5 cm 10 cm Clue: Take the area of the hole from the area of the whole! 50 cm2 – 10 cm2 = 40 cm2

Area of a rectangle = length × breadth Remember: Area of a rectangle = length × breadth length breadth Split more complicated shapes into rectangles and find the area of each rectangle then add them together. Over to you.