Vertical Angles

In geometry vertical angles are formed when two straight lines intersect. They are opposite or vertically opposite to each other and non-adjacent. The angles are also said to share the same vertex.
The most important point to note is that the angles are equal or congruent.
Vertical angles are called vertical angles because they share the same vertex. Don’t confuse the word with ‘vertical’ which means upright or the opposite of horizontal.

From the figure above we can see that four angles have been formed when two lines intersect. Each opposite pair angles are called vertical angles and always congruent.
The angles in red are equal. That is the angle ∠JPM and ∠JPK are equal, this is the same for the blue angles ∠LPJ = ∠MPK.

Facts