The right-angled triangle on the right has sides 6, 8, and 10 units long. The triangles are mathematically similar because one is an enlargement of the other.

Right-angled triangle. A right-angled triangle is a triangle where one of the angles is 90 degrees. A right angle is represented by a square, the side opposite the right angle.

Proof of Converse of Pythagoras Theorem . Given a triangle with sides of length a, b, and c, if a 2 + b 2 = c 2, then the angle between sides a and b is a right angle.. Proof: Let ABC be a ...

A 3,700-year old Babylonian clay tablet reveals an ancient method of constructing right-angled triangles that makes it the world’s oldest and most accurate trigonometric table.

Each triple is the lengths of the three sides of a right-angled triangle, where each side is a whole number. The simplest example is (3, 4, 5); others include (5, 12, 13) and (8, 15, 17).

For a right triangle, the side opposite to the right angle is called the hypotenuse (from Greek for “stretching under”). The two remaining sides are called legs .