With this Flash-Application you can calculate the different
sides and angles of a right-angeld triangle. You can click
at the red circles to modify the triangle.
You can also type specific values in the inputfields
below the animation.

Under the following link you can find similar programm over
the construction of triangles: animation

The Pythagorean theorem

The most important theorem to calculate the sides of an
right-angled triangle is the Pythagorean theorem.

To find out the length of an unknown side, you can
convert the theorem to: