# Orthocenter of a triangle

- Author:
- Josh Ryan, Tim Brzezinski

- Topic:
- Orthocenter

Recall that 3 or more lines are said to be concurrent if and only if they intersect at exactly 1 point.
The

**ORTHOCENTER**of a triangle is the point of concurrency of the**LINES THAT CONTAIN**the triangle's**3 ALTITUDES**. In the applet below,**point O**is the**orthocenter**of the triangle. Move the white vertices of the triangle around and then use your observations to answer the questions below the applet.Is it ever possible for a triangle's **orthocenter** to lie OUTSIDE the triangle? If so, under what circumstance(s) will this occur?

Is it ever possible for a triangle's **orthocenter** to lie ON THE TRIANGLE ITSELF? If so, under what circumstance(s) will this occur? And where on the triangle will it lie?

Is it ever possible for a triangle's **orthocenter** to lie INSIDE the triangle? If so, under what circumstance(s) will this occur?