Supplementary angle with compass and straightedge
(For assistance see www.mathopenref.com/constsupplementaryangle.html)
1.Construct the supplementary angle to the angle shown. Use protractor to measure each angle and verify they add to 180°
2. Construct the supplementary angle of each of the three angles in the triangle. Measure each supplementary angle and add the three of them up. What should the sum be?