If we know the sides of a triangle - we can always use the
Pythagorean Theorem backwards in order to determine if we have a
right triangle, this is called the converse of the Pythagorean
Theorem.
When working with the Pythagorean theorem we will sometimes
encounter whole specific numbers that always satisfy our equation -
these are called a Pythagorean triple. One common Pythagorean
triple is the 3-4-5 triangle where the sides are 3, 4 and 5 units
long.
There are some special right triangles that are good to know,
the 45°-45°-90° triangle has always a hypotenuse √2 times the
length of a leg. In a 30°-60°-90° triangle the length of the
hypotenuse is always twice the length of the shorter leg and the
length of the longer leg is always √3 times the length of the
shorter leg.
Video lesson: Find the value of x in the right
triangle.