Copy of Triangle Sum Theorem
Prove that the 3 interior angles of a triangle add to equal 180 degrees.
Drag the points of triangle ABC around and turn on the checkboxes to discover the relationship between the three interior angles of a triangle.
Add up the 3 angles of the triangle. What do they add up to?
Turn on the "draw auxiliary lines" checkbox. What is true about these lines?
Turn on the "Show alternating interior angles" checkbox. What do you know about these types of angles?
What is the measure of a straight line?
Use the information you have learned so far to help you fill in the blanks of the proof
What should go in the blank for #2 on the proof?
What should go in the blank for #4 in the proof?
What should go in the blank for #5 in the proof?