Orthocenter - 2019
Constructing the Orthocenter
Steps to construct orthocenter.
Step 1: Use
to construct the line through A and perpendicular to BC.
Step 2: Use
to construct the line through B and perpendicular to AC.
Step 3: Use
to construct the line through C and perpendicular to AB.
Each line you constructed above contains an altitude of the triangle.
Step 4: Use
to place a point where the altitudes intersect.
Step 5: Use
to add a label to this point where the altitudes intersect.
![Toolbar Image](https://www.geogebra.org/images/ggb/toolbar/mode_orthogonal.png)
![Toolbar Image](https://www.geogebra.org/images/ggb/toolbar/mode_orthogonal.png)
![Toolbar Image](https://www.geogebra.org/images/ggb/toolbar/mode_orthogonal.png)
![Toolbar Image](https://www.geogebra.org/images/ggb/toolbar/mode_intersect.png)
![Toolbar Image](/images/ggb/toolbar/mode_showhidelabel.png)
The point where all the altitudes intersect is called the orthocenter.
To answer the questions below, it might help to
measure each angle of the original triangle ABC.
![Toolbar Image](/images/ggb/toolbar/mode_angle.png)
1. For what type of triangle is the orthocenter outside the triangle?
Select all that apply
- A
- B
- C
2. Move your triangle around so that the orthocenter is on a vertex. What is true about the triangle when this happens?
Select all that apply
- A
- B
- C
3. Move your triangle so that vertex A is directly above on a vertical line from the orthocenter. What is true about the triangle when this happens?
Select all that apply
- A
- B
- C