How To Find The Area Of An Unusual Shape

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Area of different shapes

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How To Find The Area Of An Unusual Shape

  1. 1. How to find the Area of this unusual shape 45 55 22 20
  2. 2. This shape is actually 2 rectangles 45 55 22 20
  3. 3. So we need to find the area of each rectangle 45 55 22 20
  4. 4. The blue rectangle is 45 wide by ? long 45 55 22 20 ? Remember that rectangles have the two opposites sides equal.
  5. 5. We to have find out ? 45 55 22 20 ? So that is 55 - 20 35 - the width of the blue rectangle.
  6. 6. So the Area of the blue rectangle is 45 X 35 which is: 45 55 22 20 1575
  7. 7. So now we only have to find out the Area of the pink rectangle and add it to the blue rectangle 45 55 22 20 1575
  8. 8. We know the pink rectangle is 22 long by 20 wide so all we have to do is multiply the two numbers. 45 55 22 20 X = 440 1575
  9. 9. So now we have the Area of both rectangles and we need to add them together 1575 440
  10. 10. So the Area of our unusual shape is 45 55 22 20 1575 440 + = 2015
  11. 11. Now try these other shapes by clicking on them Practical Application 1 Practical Application 2 Practical Application 3 15 20 36 8 10 24 10 8 22 13
  12. 12. A rectangle and a triangle 36 Remember the area of a triangle is length X breadth divided by 2. A = l X b 2 Click here to return to try the other shapes Click here to check answer  20 15
  13. 13. The formula for the Area of a circle is: A = π r 2 What is the area of the blue part of the donut Click here to return to try the other shapes Click here to check answer  8 10
  14. 14. So that is 2 circles Confused click on this picture if you need help Click here to return to try the other shapes Click here to check answer  10 8
  15. 15. The formula for the Area of a circle is: A = π r 2 So you have to take away the area of the small circle from the area of the big one. But first find out the radius of the larger circle which is 10 + the radius of the smaller circle (8) Click here to return to try the other shapes Click here to check answer  10 8
  16. 16. So add the area of the three rectangles or Find the Area of the large rectangle and take away the Area of the smaller inside one. Click here to return to try the other shapes Click here to check answer  24 10 8 22 13 24 22 10 13
  17. 17. How much will it cost to carpet the lounge room and hallway of this house at $55 per sq.m. 5m 2m 1m 3.5m Click here to return to try the other shapes Click here to check answer 
  18. 18. How much will it cost to tile the kitchen and dining room of this house at $68 per sq.m. 5m 2m 1m Kitchen Dining Room The kitchen is 4m by 2.4m Click here to return to try the other shapes Click here to check answer 
  19. 19. Here are the four walls of a bedroom – How much would it cost to paint them at $3.50 per Sq. M. Door Window Window 1m 1.8m 1.5m 1.5m 1.3m 1.7m Remember we don’t want to paint the door or windows, so think about how you will do it Help Click here to check answer  4.5m 4.5m 3.2m 3.2m 2.5m 2.5m 2.5m 2.5m
  20. 20. How to do it! <ul><li>Find out the area of the four walls and take away the area of the door and windows </li></ul><ul><li>Then multiply the answer by the amount it costs to paint 1 sq. m. </li></ul><ul><li>E.g. for wall with door </li></ul>Area of yellow rectangle = 4.5 X 2.5 - Area of blue rectangle = 1 X 1.8 Return to problem
  21. 21. Answers 408 398 817.14 Click on the answer you have 540 420 Practical Application 1 Practical Application 2 $14.85 $1365.20 $4325.00 $1078.00 $1960.00 $2378.75 $1485.80 $43.25 480 528 871.41 300 480 1018.29 201.14 $171.85 $33.70 $350.00 $117.95 Practical Application 3 24 10 8 22 13 8 10 15 20 36
  22. 22. Yes that’s right
  23. 23. Sorry that is wrong – check your workings – try again! Practical Application 1 Practical Application 2 Practical Application 3 15 20 36 8 10 24 10 8 22 13

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