how to determine the possition of orthocentre of triangle?i.e inside,outside or on the tringle.

The orthocenter is not always inside the triangle. If the triangle is obtuse , it will be outside. To make this happen the altitude lines have to be extended so they cross. Adjust the figure above and create a triangle where the orthocenter is outside the triangle. Follow each line and convince yourself that the three altitudes, when extended the right way, do in fact intersect at the orthocenter.

Approved