Learning about Exterior Angles

Introduction

Now that you've learnt about Triangles and other laws related to angles, it is time to put them together to discover a new interesting property about triangles. :)
in the image above shows [math]\bigtriangleup[/math]ABC, when the vertex BC is extended to form CD, a new angle is formed. 

[math]\angle[/math]d is formed. it is the exterior angle to [math]\bigtriangleup[/math]ABC.


in the image above shows ABC, when the vertex BC is extended to form CD, a new angle is formed. d is formed. it is the exterior angle to ABC. 

AIM

The aim of today's activity is to discover the relationship between angle d and the other angles in the triangle.

Task

1.