This is a prototype of JavaSketchpad, a World-Wide-Web component of The Geometer's Sketchpad. Copyright ©1990-1997 by Key Curriculum Press, Inc. All rights reserved. Portions of this work are being funded by the National Science Foundation (awards DMI 9561674 & 9623018).
Put triangle ABC together with the rotated copy of the triangle to make a parallelogram.
Then find a formula for the area of a triangle.
Double-click the "Show" buttons to see measurements for base and altitude.