Quadrilaterals — Properties Of Triangles And

In a right triangle with hypotenuse ( c ), ( a^2 + b^2 = c^2 ). Conversely, if ( a^2 + b^2 = c^2 ) in a triangle, the angle opposite ( c ) is right.

Proof (synthetic): Through a vertex, draw a line parallel to the opposite side. Alternate interior angles give the sum of the three angles as a straight angle. properties of triangles and quadrilaterals