Area of rectangles

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Area of rectangles

  1. 1. Objective : Calculate the areaObjective : Calculate the areaof rectangles.of rectangles.o Area is the space inside a 2D shape.Area is the space inside a 2D shape.o Squares and oblongs are bothSquares and oblongs are bothrectangles.rectangles.
  2. 2. What is area measured in?What is area measured in? Area is measured in SQUAREArea is measured in SQUARECENTIMETRES.CENTIMETRES. A square centimetre is a square in whichA square centimetre is a square in whichall the sides measure 1 cm.all the sides measure 1 cm. Area is also measured in SQUAREArea is also measured in SQUAREMETRES.METRES. A square metre is a square in which all theA square metre is a square in which all thesides measure 1 metre.sides measure 1 metre.
  3. 3. How do we calculate area?How do we calculate area? It’s really easy!It’s really easy! Measure the length.Measure the length. Measure the width.Measure the width. Multiply the length X width toMultiply the length X width tocalculate the area!calculate the area!
  4. 4. Example:-Example:-10 cm5 cm10 cm X 5 cm = 50 square centimetres = Area
  5. 5. How do we write units ofHow do we write units ofmeasurement for area?measurement for area? 50 square centimetres would be written as50 square centimetres would be written as50cm50cm22 32 square metres would be written as32 square metres would be written as32m32m22
  6. 6. When do you use cmWhen do you use cm22or mor m22?? Which unit of measurement would you useWhich unit of measurement would you useto measure these areas?to measure these areas? Area of a floppy disk?Area of a floppy disk? Area of a CD cover?Area of a CD cover? Area of a table?Area of a table? Area of a netball court?Area of a netball court?
  7. 7. But what if you want to calculateBut what if you want to calculatethe area of an irregular shape?the area of an irregular shape? What if the shape has more than 4 sides?What if the shape has more than 4 sides? How can you doHow can you doLength X WidthLength X Widthwhen there isn’t a length and there isn’t awhen there isn’t a length and there isn’t awidth?width?
  8. 8. YOU HAVE TO MAKEYOU HAVE TO MAKERECTANGLES!RECTANGLES! Look at this shape. How could youLook at this shape. How could youcalculate the area?calculate the area?10cm6cm6cm4cm
  9. 9. You have to create more than oneYou have to create more than onerectangle.rectangle. Like this!Like this!10cm6cm6cm4cm4cmA = 6cm X 4cm = 24cm2B = 6cm X 4cm = 24cm2A + B = Area24cm2+ 24cm2= 48cm2AB
  10. 10. So to calculate the area of anSo to calculate the area of anirregular shapeirregular shape Split the shape into at least twoSplit the shape into at least tworectangles.rectangles. Calculate the area of each one.Calculate the area of each one. Add the two together.Add the two together. You’re done!You’re done!

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