Year 6 - Maths
Use the area of a triangle to calculate unknown measurements
Area, perimeter, position and direction
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will explain how to calculate the area of a parallelogram and a triangle. They will describe the relationship between scale factors and side lengths. They will describe positions in all 4 quadrants.
Lesson Summary
You will learn to calculate unknown dimensions of a triangle with a specified area.
Key Notes
- The area of a triangle is half the area of a parallelogram with the same perpendicular base and height.
- The area of a triangle can be calculated using the formula area = base × perpendicular height ÷ 2
- A missing perpendicular height in a triangle can be found using the formula area × 2 ÷ base
- A missing base in a triangle can be found using the formula area × 2 ÷ perpendicular height
Vocabulary To Learn
- Base: The base is the side which is perpendicular to the shape's height.
- Perpendicular: Two lines are perpendicular if they meet at a right angle.
Common Mistakes To Avoid
- When drawing triangles with a given area pupils may create a factor pair of the triangle's area when drawing the base and perpendicular height. The factor pair refers to the surrounding parallelogram.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The area of a triangle is half the area of a parallelogram with the same perpendicular base and height. The area of a triangle can be calculated using the formula area = base × perpendicular height ÷ 2.
2. Use this key word in a maths sentence and explain it clearly. 'Base'
The base is the side which is perpendicular to the shape's height. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When drawing triangles with a given area pupils may create a factor pair of the triangle's area when drawing the base and perpendicular height. The factor pair refers to the surrounding parallelogram. Correction: For pupils who are making this mistake, encourage them to sketch the parallelogram around the triangle, reminding them to double the triangle area before finding the factor pairs.
More Lessons In This Unit
- Describe the relationship between scale factors and perimeters of two shapes Study Guide
- Draw and complete simple shapes by plotting positions on the full coordinate grid Study Guide
- Draw and translate simple shapes on the full coordinate grid Study Guide
- Explain how to calculate the area of a parallelogram Study Guide
- Explain how to calculate the area of a triangle Study Guide
- Reflect simple shapes in the axes on a full coordinate grid Study Guide
- Solve problems involving area and perimeter Study Guide
- Solve problems involving missing coordinates Study Guide
- Use the area of a parallelogram formula to calculate unknown measurements Study Guide
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