Using Perpendicular Lines to Prove Angles Congruent

In this video you will learn the correct steps for using perpendicular lines to prove angles congruent in a logic proof.

Perpendicular lines form right angles at the location of intersection.

In the example in the video we are given the information that $\overline{AC}\perp\overline{BD}$ , so mark the right angles in the diagram. On the statement-reason proof chart, write down the given information.

Now, we know that $\angle ACB$ and $\angle ACD$ are right angles because perpendicular lines form right angles. Since they are both right angles, we can then say that $\angle ACB \cong \angle ACD$ because all right angles are congruent.

With only a small piece of information, $\overline{AC} \perp \overline{BD}$ , we found that $\angle ACB \cong \angle ACD$ .