Interactive · 1 question
+1 contributors
Contributors
Examples: Perpendiculars and Altitudes
Perpendicular
One line is perpendicular to another line when the angle between them is 90 degrees.
In the image above, the angle between line segment AB and AC is 90 degrees, therefore those two line segments are perpendicular.
We use a little right angle, or square, to indicated perpendicularity:
Altitude
In general, altitude means height.
For triangles, an altitude is a line going through a point that is perpendicular to the opposite side (of that point). Every triangle has 3 altitudes.
The altitudes are not always inside the triangle:
How many altitudes are inside an equilateral triangle?