Exploring the products: (AF)(BD)(CE) and (AE)(BF)(CD)

by: BJ Jackson

In this section, we look at what happens to the products as the point p changes positions in the interior of the triangle and as the lengths of the sides of the triangle change.

We start by making our diagram and finding the products. GSP will do all of this for us and we find our intitial values for the picture below to be:

and .

The products are the same! Now, we have to wonder if this is always true or is this just a random happening. To try and figure this out, we will vary the location of point P and the lengths of the sides. If this product continues to be the same, then we will be able to make a conjecture that the products are always the same no matter where the point p is located in any triangle.

So, we will try some different locations for P and find the products.

The products remain constant. Click here for a GSP sketch that will animate the point p inside the triangle. One will see that no matter where the point goes, the product stays the same.

Now, we will vary the size and the shape of the triangle and check the products.

Again, the products remain the same. If one wants change the sides of the triangle, click on the link above for the animation and you can vary the shape and size of the triangle.

This leads us to believe that our conjecture that the products are always equal is true. Another way of stating the conjecture is to say that the ratios of the products equals 1 which is what will actually be proven.

A proof of the conjecture

Return to the final write-up page

Back to BJ's Page