Basic Triangle Properties

Joseph Rudin III, Oct 3, 2016

This book explores the basic geometric properties of triangles, including how to classify them based on their sides and angles, the triangle sum conjecture, and the exterior angle theorem.


  • 1. Classifying Triangles
  • 2. Triangle Sum Conjecture
  • 3. Exterior Angles Theorem

1.

Classifying Triangles

Sides and Angles
Triangles can be classified based on two different properties, their sides and their angles. This worksheet explores these different classifications.
In the applet below, change the side lengths of the triangle with the sliders. Notice how the classification based on sides changes with different combinations of side lengths. Next, pay attention to how the classification based on angles changes with different combinations of angle values (you can change these angle by changing the side lengths).
Choose the correct classification based on the definition
Triangles with all angles less than 90°
Triangles with one angle greater than 90°
Triangles where one angle equals 90°
Triangles where all the sides are a different length.
Triangles where all the sides are the same length.
Triangles where two sides are the same length.
– Joseph Rudin III

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