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Area Of A Triangle

Author:Jennifer Mallory, GeoGebra Materials Team

Discovering the Area of a Triangle

In this activity, you will investigate how to find the area of a triangle.

Follow the directions below to investigate how to find the area of a triangle.

Investigation: 1) Adjust the base slider so that the base is 10 units. 2) Move point D so that the triangle is a right triangle and note the area of the triangle.            3) Move the "Hint" slider and identify the new figure. Answer the questions below.

Question 1

What figure was created after you moved the "Hint" slider?

Check my answer

Question 2

What is the area of the new figure that was created when moving the slider?

Select all that apply
  • A
  • B
  • C
  • D
Check my answer (3)
Investigation: 1) Make sure the base slider is still located at 10 units. 2) Move point D to make an obtuse triangle and note the area of the triangle.                          3) Move the "Hint" slider and identify the new figure. Answer the question below.

Question 3

What figure was created after you moved the "Hint" slider?

Select all that apply
  • A
  • B
  • C
  • D
Check my answer (3)

Question 4

What is the area of the new figure that was created when moving the slider?

Select all that apply
  • A
  • B
  • C
  • D
Check my answer (3)
Investigation: 1) Adjust the base slider so that the base is 10 units. 2) Move point D so that the triangle is an acute triangle and note the area of the triangle.                          3) Move the "Hint" slider and identify the new figure. Answer the questions below.

Question 5

What figure was created after you moved the "Hint" slider?

Select all that apply
  • A
  • B
  • C
  • D
Check my answer (3)

Question 6

What is the area of the new figure that was created when moving the slider?

Select all that apply
  • A
  • B
  • C
  • D
Check my answer (3)

Question 7

What conclusion can you make based on the area of of the new figures and the area of the three triangles?

Select all that apply
  • A
  • B
  • C
  • D
Check my answer (3)

Question 8

Your Turn: 1) Change the height and the base using values of your choosing. 2) Create a right, obtuse, and acute triangle using your chosen base and height. 3) Compare the areas. How does the area of the quadrilaterals compare to the area of the triangles? Why do you think this is so?

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