GeoGebra Classroom

# Area of a Trapezium finding and comparing

First can you work out the formula for the area of a trapezium? Rotate out a second trapezium for a clue. Compare the shape to the formula for a parallelogram. Check your answer with the "show area formula" box. Second can you change the shape (using the 3 blue corner dots and the height dot) to make other shapes? See if you can find a rhombus, parallelogram, rectangle, square and any tyoe of triangle. How does the formula change for the different shapes? Look at the values for a and b on the shape and in the formula. Use the rotate slider to see that it's still always a parallelogram.

## Question 1

Move the height to 5, a = 7, b = 13. Use the rotate slider. What is the area of the parallelogram? What is the area of the trapezium? Check the formula box, so you can see the formula used.

## Question 2

Move the height to 3, a = 4, and b = 8. Use the rotate slider. What is the area of the parallelogram? What is the area of trapezium?

## Question 3

﻿Without using the applet calculate the area of a trapezium with a height of 6, a = 4, and b = 12? Now use the applet above to see if you anwser was correct? In the box below type in the area you found and answer if you were correct.

## Question 4

In your own words type out how you calculate the area of a trapezium.