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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.