Form 3 Mathematics

Mid-point Theorem

This is a prototype of JavaSketchpad, a World-Wide-Web component of The Geometer's Sketchpad. Copyright & copy ; 1990-1998 by Key Curriculum Press, Inc. All rights reserved. Portions of this work were funded by the National Science Foundation (awards DMI 9561674 & 9623018).
This page is best viewed by IE4 or Netscape Communicator (java-capable browsers).
Investigation

ABC is a triangle. D and E are mid-points of AB and AC respectively.

Drag A, B and C. Observe the line segments BC and DE. What can you say?

Can you prove your conjectures?

 Sorry, this page requires a Java-compatible web browser.

Mid-point Theorem:

In a triangle ABC, if D and E are the mid-points of AB and AC respectively, then DE//BC and the length of DE is half of the length of BC.

Further question

If ABC is a triangle so that D is the mid-point of AB. E is a point on AC so that the length of DE is half of the length of BC.

Is it true that DE//BC ? Think about it before you click "Answer". 

 Sorry, this page requires a Java-compatible web browser.

[Back to main page][Back to Javasketchpad page]