Proving a Triangle is Acute, Right or Obtuse
Using Pythagorean's Theorem to Find out if triangles are acute, obtuse, or right.
In the applet below, notice that the sum of the squares of the two shorter sides is equal to the square of the longest side when the triangle is a right triangle.
What is the relationship between the sum of the squares of the shorter sides and the square of the longest side when the triangle is acute or obtuse.