Education Technology

TAS: Jack’s Tile Problem – Exploring the Area Rule for Triangles

by Stephen Julian


The objective of this activity is to show students how the area of a triangle formula Area = 1/2.a.b.sin(C) can be used to find the area of non-right angle triangles.


  • Area
  • Triangle
  • Non-right angle

About the Lesson

In this activity, students copy a TI-Nspire document onto their handhelds. They then change the shape of a triangle and capture the dimensions into a spreadsheet. In the first part of the activity, they use the rule Area = 1/2.b.h to confirm the areas of the triangles. In the second part of the activity, they use the rule Area = 1/2.a.b.sin(C) to verify the areas. They finish the activity by moving parts of a triangle to learn why both formulas arrive at the same result.