Exterior Angle
Add the measure of angle A and angle B. What is the sum?
What do you notice about the sum?
Drag vertices A and B to new locations. Now, add the new measures of angle A and angle B. Is the sum the same as angle ACD?
Add the measure of angle A and angle B. What is the sum?
What do you notice about the sum?
Drag vertices A and B to new locations. Now, add the new measures of angle A and angle B. Is the sum the same as angle ACD?