# A Trapezium and its properties

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### Learning objectives

- A quadrangle with only two opposite sides parallel is called a trapezium, or trapezoid.
- The parallel sides are called the bases of the trapezium and the other two sides are called the legs or the lateral sides.
- If the legs are equal in length, then this is an isosceles trapezium.
- The distance between the bases is called height of trapezium.

### Notes for teachers

### Activity No # 1. Properties of a trapezium.

- Estimated Time :40 minutes.
- Materials/ Resources needed:

Laptop, geogebra file, projector and a pointer.

- Prerequisites/Instructions, if any

- Knowledge about parallel lines, angles and diagnols.

- Multimedia resources: Laptop.
- Website interactives/ links/ / Geogebra Applets: This file has been taken from www.geogebratube.org

- Process:

- Show the geogebra file and explain its properties by asking the questions listed below.

- Developmental Questions:

- What is a trapezium ?
- How many sides does it have ?
- What can be said about the pair of sides ?
- Identify the diagnols. Are they equal ?
- What would be the sum of 4 angles of the trapezium ? Why so ?
- What would be the sum of its two allied angles ?
- Are the two pairs of sides of a trapezium equal ?

- Evaluation:

Are the students able to apply the theorems of parallel lines - transversal to prove the properties.

- Why are allied angles of the trapezium supplementary ?
- Are the diagnols equal ?
- Is trapezium a parallelogram ?

- Question Corner:

- List the properties of a trapezium.
- What properties of other quadrilaterals does it share. Compare with other quadrilaterals.