Area of compound figures

๐Ÿ“˜ Compound Figure

  • A compound figure (or composite shape) is a shape made up of two or more simple shapes.
    Example: Rectangle + Triangle, Square + Circle, etc.

๐Ÿงฉ Break Into Simple Shapes

  • To find the area easily, split the compound figure into simple shapes you already know:
    โœ… Square
    โœ… Rectangle
    โœ… Triangle
    โœ… Circle (if given)

๐Ÿ“ Area Formulas You Must Know

ShapeFormulaEmoji
โฌ› RectangleArea = Length ร— Breadth๐Ÿ“ร—๐Ÿ“
โ—ผ๏ธ SquareArea = Side ร— Side๐Ÿ”ฒ
๐Ÿ”บ TriangleArea = ยฝ ร— Base ร— Heightโœ–๏ธโž—2
โšช Circle*Area = ฯ€ ร— rยฒ (use only if required at grade level)๐Ÿ”ต

๐Ÿ’ก Add or Subtract Areas

  • If shapes are joined, add their areas โž•
  • If a part is cut out, subtract the removed area โž–

๐Ÿ” Steps to Find the Area of a Compound Figure

1๏ธโƒฃ Split the figure into smaller known shapes ๐Ÿงฉ
2๏ธโƒฃ Label the lengths clearly โœ๏ธ
3๏ธโƒฃ Write formula for each shape ๐Ÿ“˜
4๏ธโƒฃ Find area of each part ๐Ÿ”ข
5๏ธโƒฃ Add or subtract the areas to get the total area โœ…

๐ŸŽฏ Important Tips

โœจ Convert all units to the same unit before calculation (cm, m).
โœจ The final answer should be in square units (cmยฒ, mยฒ).
โœจ Draw lines to separate shapes if neededโ€”this makes the problem easier! โœ๏ธ๐Ÿ“


๐ŸŒˆ Example (Simple)

A figure is made of:
๐Ÿ“ 1 rectangle + 1 triangle

โžก๏ธ Find area of rectangle
โžก๏ธ Find area of triangle
โžก๏ธ Add them to get the total area ๐ŸŽ‰


โœ… Remember!

  • Compound = Many Shapes Combined ๐Ÿงฉ
  • Area means the space inside a shape ๐ŸŒ
  • Use formulas + addition/subtraction to find the total area ๐Ÿงฎ

__________ square centimetres

  • Divide the figure into rectangles:
  • Start with rectangle A. Rectangle A is 11 centimetres wide and 11 centimetres tall.
  • Multiply: 1111=121
  • The area of rectangle A is 121 cm2.
  • Look at rectangle B. Rectangle B is 22 centimetres wide and 14 centimetres tall.
  • Multiply: 2214=308
  • The area of rectangle B is 308 cm2.
  • Now add the areas of the two rectangles:
  • 121 cm2+308 cm2=429 cm2
  • The area is 429 square centimetres.

_________square kilometres

  • Divide the figure into rectangles:
  • Start with rectangle A. Rectangle A is 17 kilometres wide and 13 kilometres tall.
  • Multiply: 1713=221
  • The area of rectangle A is 221 km2.
  • Look at rectangle B. Rectangle B is 7 kilometres wide and 22 kilometres tall.
  • Multiply: 722=154
  • The area of rectangle B is 154 km2.
  • Now add the areas of the two rectangles:
  • 221 km2+154 km2=375 km2
  • The area is 375 square kilometres.

___________square millimetres

  • Divide the figure into rectangles:
  • Start with rectangle A. Rectangle A is 5 millimetres wide and 23 millimetres tall.
  • Multiply: 523=115
  • The area of rectangle A is 115 mm2.
  • Look at rectangle B. Rectangle B is 17 millimetres wide and 4 millimetres tall.
  • Multiply: 174=68
  • The area of rectangle B is 68 mm2.
  • Now add the areas of the two rectangles:
  • 115 mm2+68 mm2=183 mm2
  • The area is 183 square millimetres.

Let’s practice!๐Ÿ–Š๏ธ