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Triangles and composite rectangles
Triangles and composite rectangles
Example 1
A triangle has base 8cm and perpendicular height 4cm. Find its area, in cm2.
Triangle with perpendicular heightDiagram not to scaleShow worked answer
Answer: 16
- Area = ½ × base × perpendicular height = ½ ×8×4=16cm2.
Example 2
A parallelogram has base 14cm and perpendicular height 7cm. Find its area, in cm2.
ParallelogramDiagram not to scaleShow worked answer
Answer: 98
- Use the perpendicular height, not the slanted side.
- 14×7=98cm2.
Example 3
An L-shape is a 16cm by 11cm rectangle with a 5cm by 5cm corner removed. Find its area, in cm2.
L-shaped regionDiagram not to scaleShow worked answer
Answer: 151
- Subtract the missing rectangle.
- 16×11−5×5=151cm2.
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