Understanding Altitudes in Triangles
In geometry, the altitude of a triangle is the perpendicular segment from a vertex to the line containing the opposite side. Depending on the type of triangle, the altitude can either lie inside or outside the triangle.

Types of Triangles and Their Altitudes
- **Acute Triangle**: All angles are less than 90 degrees.
- *Altitude*: Lies inside the triangle.
- **Right Triangle**: One angle is exactly 90 degrees.
- *Altitude*: The altitude from the right angle vertex lies inside the triangle. The altitudes from the other two vertices will also be inside.
- **Obtuse Triangle**: One angle is greater than 90 degrees.
- *Altitude*: The altitude from the vertex with the obtuse angle will lie outside the triangle.

Key Point: Identifying the Triangle with Outside Altitude
- The only triangle that will have its altitude outside is the **Obtuse Triangle**.
- *Reason*: The altitude drawn from the obtuse angle must extend beyond the opposite side to form a right angle, leading to an external position.

Conclusion
In summary, if you are given a triangle and need to determine if its altitude lies outside, look for the obtuse angle. Only in an obtuse triangle does the altitude extend beyond the triangle's interior.