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Composite perimeter and area
Composite perimeter and area
Example 1
An L-shape is a 12cm by 10cm rectangle with a 3cm by 4cm corner removed. Find its area, in cm2.
L-shaped regionDiagram not to scaleShow worked answer
Answer: 108
- Subtract the missing rectangle.
- 12×10−3×4=108cm2.
Example 2
An L-shape is a 16cm by 9cm rectangle with a 5cm by 3cm corner removed. Find the complete outer perimeter, in cm.
L-shaped regionDiagram not to scaleShow worked answer
Answer: 50
- The removed outside lengths are replaced by equal inside lengths.
- Add all six edges: 16+6+5+3+11+9=50cm.
Example 3
An L-shape is a 16cm by 8cm rectangle with a 5cm by 2cm corner removed. Find its area, in cm2.
L-shaped regionDiagram not to scaleShow worked answer
Answer: 118
- Subtract the missing rectangle.
- 16×8−5×2=118cm2.
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