Exterior Angle Theorem Game
The Exterior Angle Theorem relates an exterior angle of a triangle to its two opposite interior angles. The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles (the two interior angles that are not adjacent to the exterior angle). Scroll down the page for a more detailed explanation.
 
The game generates problems where you must find either the exterior angle or one of the remote interior angles. If you give a wrong answer, the game will give you the right answer.
 
Triangle Sum Theorem
Exterior Angle Theorem
 

Exterior Angle Challenge

Score:

0 / 0

Find the measure of the angle $x^\circ$ in the diagram.

Check Answer

Next Question Restart Game

 

How to Play the Exterior Angle Theorem Game
In this game, you need to find the missing angle in a triangle using the Exterior Angle Theorem Theorem which states that the exterior angle is the sum of the two opposite interior angles. The game generates problems where you must find either the exterior angle or one of the opposite interior angles.
Here’s how to play:

1. Find the Angle: Use the Exterior Angle Theorem to find the missing angle x.
   
2. Enter Your Answer: Type your answer for the angle.
   
3. Check Your Work: Click the Check button (or press the Enter key). The game will tell you if you’re correct. If you are wrong, you will be shown the correct answer.
   
4. Get a New Problem: Click the Next button (or press Enter again) for a new problem.
   Your score is tracked at the top, showing how many you’ve gotten right out of the total you’ve tried.
5. Restart Game Click “Restart Game” to restart the game.
    
   

The Exterior Angle Theorem
The theorem states that the exterior angle is the sum of the two opposite (remote) interior angles.
This rule holds true for every single triangle, regardless of its size or shape (whether it’s acute, obtuse, right, equilateral, isosceles, or scalene).
 
Definition
The measure of an exterior angle of a triangle is equal to the sum of the measures of the two remote interior angles (the two interior angles that are not adjacent to the exterior angle).
 
The Formula
If E is the measure of the exterior angle, and R₁ and R₂ are the measures of the two remote interior angles, the theorem states: E = R₁ + R₂
 

The video gives a clear, step-by-step approach to learn and use the Exterior Angle Theorem Theorem.

• Show Video

 

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