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area_of_rectangles_JB.ppt area rectangle
- 1. Finding the Finding the Areaof a Area of a Rectangle Rectangle
- 2. Area of aRectangle Area of a Rectangle Objectives Objectives • To calculate areas of rectangles To calculate areas of rectangles • To calculate areas of polygons To calculate areas of polygons made of rectangles made of rectangles
- 3. Area of aRectangle Area of a Rectangle Area is the measure of how much space a Area is the measure of how much space a shape takes up. We measure it in squares such shape takes up. We measure it in squares such as square centimetres or metres etc. as square centimetres or metres etc. 1 cm 1 cm 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 10 10 11 11 12 12 13 13 14 14 15 15 16 16 17 17 18 18 19 19 20 20 21 21 22 22 23 23 24 24 25 25 26 26 27 27 28 28 This rectangle takes This rectangle takes up 28 squares. up 28 squares. It has an area of 28 It has an area of 28 square centimetres square centimetres 28 cm 28 cm2 2
- 4. Area of aRectangle Area of a Rectangle It could take a long time to cover shapes in It could take a long time to cover shapes in squares. Luckily there is an quicker way. squares. Luckily there is an quicker way. 7 cm 7 cm 4 cm 4 cm × × = = 28 cm 28 cm2 2
- 5. Area of aRectangle Area of a Rectangle Use this formulae to find the area of rectangles. Use this formulae to find the area of rectangles. Area of a rectangle = length × breadth Area of a rectangle = length × breadth length length breadth breadth
- 6. Area of aRectangle Area of a Rectangle Can you find the areas of these rectangles? Can you find the areas of these rectangles? 5 cm 5 cm 3 cm 3 cm 15 cm 15 cm2 2 2 cm 2 cm 7 cm 7 cm 14 cm 14 cm2 2 7 m 7 m 7 m 7 m 49 m 49 m2 2
- 7. Area of aRectangle Area 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 cm 12 cm 6 cm 6 cm 5 cm 5 cm 7 cm 7 cm 3 cm 3 cm
- 8. Area of aRectangle Area of a Rectangle Split the shape into rectangles? Split the shape into rectangles? 12 cm 12 cm 6 cm 6 cm 5 cm 5 cm 7 cm 7 cm 3 cm 3 cm
- 9. Area of aRectangle Area of a Rectangle Find the area of each rectangle? Find the area of each rectangle? 6 cm 6 cm 5 cm 5 cm 7 cm 7 cm 3 cm 3 cm 5 × 6 = 30 cm 5 × 6 = 30 cm2 2 7 × 3 = 21 cm 7 × 3 = 21 cm2 2
- 10. Area of aRectangle Area of a Rectangle Add the areas together to find the area of the Add the areas together to find the area of the complete shape? complete shape? 30 + 21 = 51 cm 30 + 21 = 51 cm2 2 30 cm 30 cm2 2 21 cm 21 cm2 2
- 11. Area of aRectangle Area of a Rectangle Can you find the areas of these shapes? Can you find the areas of these shapes? 11 cm 11 cm 5 cm 5 cm 7 cm 7 cm 4 cm 4 cm 2 cm 2 cm 43 cm 43 cm2 2 6 m 6 m 4 m 4 m 3 m 3 m 4 m 4 m 1 m 1 m 22 m 22 m2 2
- 12. Area of aRectangle Area of a Rectangle Here is a challenge can you work out the area Here is a challenge can you work out the area of this shape with a hole in it? of this shape with a hole in it? 10 cm 10 cm 5 cm 5 cm 5 cm 5 cm 2 cm 2 cm Clue: Take the area of the hole from the area of the whole! Clue: Take the area of the hole from the area of the whole! 50 cm 50 cm2 2 – 10 cm – 10 cm2 2 = 40 cm = 40 cm2 2
- 13. Remember: Remember: Area of arectangle = length × breadth Area of a rectangle = length × breadth length length breadth breadth 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.