A line is said to be perpendicular to another line if the two lines intersect at a right angle. Explicitly, a first line is perpendicular to a second line if (1) the two lines meet; and (2) at the point of intersection the See more

The word foot is frequently used in connection with perpendiculars. This usage is exemplified in the top diagram, above, and its caption. The diagram can be in any … See more

If two lines (a and b) are both perpendicular to a third line (c), all of the angles formed along the third line are right angles. Therefore, in Euclidean geometry, any two lines that … See more

Circles
Each diameter of a circle is perpendicular to the tangent line to that circle at the point where the diameter intersects the circle.
A line segment through a circle's center bisecting a chord is perpendicular to the chord. See more

To make the perpendicular to the line AB through the point P using compass-and-straightedge construction, proceed as follows (see figure left):
• Step … See more

In the two-dimensional plane, right angles can be formed by two intersected lines if the product of their slopes equals −1. Thus defining two linear functions: y1 = a1x + b1 and y2 = a2x + b2, the graphs of the functions will be perpendicular and will make four right … See more

Triangles
The legs of a right triangle are perpendicular to each other.
The altitudes of a triangle are perpendicular to their respective See more