Area of a triangle
Area = ½ × base × perpendicular height.
The common mistake
Using a slanted side as the height, or forgetting the ½.
Instead: The height must meet the base at a right angle. Multiply base by that height, then halve.
Worked example with Guide me
A triangle has base 10 cm and height 6 cm. Find its area.
- Sugar · Base times height?Student · 60.
- Sugar · What's missing?Student · The half — 30.
Answer: 30 cm²
Try 3 practice questions
1. Base 8, height 5 — area?
Show answer
20
2. Base 12, height 7 — area?
Show answer
42
3. Area 24, base 8 — height?
Show answer
6
Quick answers
- What is the most common mistake with area of a triangle?
- Using a slanted side as the height, or forgetting the ½.
- How do I get area of a triangle right?
- The height must meet the base at a right angle. Multiply base by that height, then halve.
- Can you show a worked example?
- A triangle has base 10 cm and height 6 cm. Find its area. 30 cm²
Related concepts
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