# G.GCI.3 Orthocenter (& Questions)

- Author:
- Dan Dale, 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.**Questions:**1) Is it ever possible for a triangle's

**orthocenter**to lie OUTSIDE the triangle? If so, under what circumstance(s) will this occur? 2) Is it ever possible for a triangle's

**orthocenter**to lie ON THE TRIANGLE ITSELF? If so, under what circumstance(s) will this occur? 3) If your answer for (2) was "YES", where on the triangle did

**point O**lie? 4) Is it ever possible for a triangle's

**orthocenter**to lie INSIDE the triangle? If so, under what circumstance(s) will this occur?

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