Year 7 - Maths
Calculating missing side lengths from the area of a trapezium
Perimeter and area
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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 investigate how to calculate the area and perimeter of rectilinear shapes, and composite shapes using rectangles and triangles. They will also derive simple area formulae.
Lesson Summary
You will learn to calculate a missing side length from the area of a trapezium.
Key Notes
- The formula can be used to calculate the area of a trapezium.
- The area of a trapezium can be used to calculate a missing side length.
- It cannot be used to calculate one of the slanted sides.
Vocabulary To Learn
- Trapezium: A trapezium is a quadrilateral with exactly one pair of parallel opposite sides.
- Trapezia/trapeziums: The plural of trapezium can be referred to as trapezia or trapeziums.
Common Mistakes To Avoid
- Pupils may forget to divide by 2 when calculating the area of a trapezium.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The formula can be used to calculate the area of a trapezium. The area of a trapezium can be used to calculate a missing side length.
2. Use this key word in a maths sentence and explain it clearly. 'Trapezium'
A trapezium is a quadrilateral with exactly one pair of parallel opposite sides. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils may forget to divide by 2 when calculating the area of a trapezium. Correction: The area of a trapezium is half of the area of the parallelogram formed from two identical trapeziums.
More Lessons In This Unit
- Area of a trapezium Study Guide
- Area of a triangle Study Guide
- Area of composite rectilinear shapes Study Guide
- Calculating missing lengths with perimeter of polygons Study Guide
- Calculating missing side lengths from the area of composite rectilinear shapes Study Guide
- Checking understanding of perimeter and area Study Guide
- Finding the perimeter of polygons Study Guide
- Perimeter with composite rectilinear shapes Study Guide
- Problem solving with perimeter and area Study Guide
- Securing understanding of perimeter and area Study Guide
- Using the formula for the area of a triangle Study Guide
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