What are geometry proofs of perpendicular lines?

Answer by  cgroverla (516)

The basic concept of establishing that two lines are perpendicular is to take two points equidistant from the point of intersection on one of the lines, and one point on the other intersecting line. Then show that the two congruent triangles formed by the points you have drawn and the point of intersection each satisfy the Pythagorean Theorem.

Answer by  Ligia (18)

The lines must intersect in one point. and form right angles. All angles are congruent. The product of their slope must be negative 1. The lines must belong to the same plane. If lines are not in the same plane, then they are perpendicular if and only planes are perpendicular to each other.