A Triangle's Angles

The sum of the measures of the interior angles of any triangle is 180°.

This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

Drag the red point to change the shape of the triangle.
Drag the blue points to rotate the vertices.

Do you see that the interior angles together make a straight angle?
Do you also see how to determine the area of the triangle?

Steve Kifowit, Created with GeoGebra