The theorem that the three altitudes of a triangle meet in a single point, the orthocenter, was first proved in a 1749 publication by William Chapple.

The orthocenter is the intersecting point for all the altitudes of the triangle. The point where the altitudes of a triangle meet is known as the Orthocenter. In the below mentioned diagram orthocenter is denoted by the letter ‘O’. There is no direct formula to calculate the orthocenter of the triangle. It lies inside for an acute and outside for an obtuse triangle.

Altitudes are nothing but the perpendicular line ( AD, BE and CF ) from one side of the triangle ( either AB or BC or CA ) to the opposite vertex. Vertex is a point where two line segments meet ( A, B and C ).