(Newer Version): Set 3 coordinates and connect them to create a TRIANGLE. Bring up a Virtual Protractor to measure the angles. (a) Use the slider variables to set x1: y1: and click the green Set Pt button confirm the START point. (b) Use the sliders again to set x2: y2: and Set Pt to confirm the second point. (c) Set and confirm x3: y3: in the same way. (d) Click the Draw button to join the 3 coordinate points. (e) Click Show Protractor to show/ hide the Virtual Protractor close the triangle. (f) Drag the protractor and use RIGHT / LEFT rotate the protractor. (g) Read the size of each angle and discover that the SUM of the three angles is 180º.
