When you have 2 lines that bisect one another, the point that the 2 lines meet is called the vertex. The 2 angles that are right next to one another on the same line, they are called linear angles. Linear angles always add up to 180°. The 2 angles that do not share a line are called opposite angles, or vertical angles. Opposite angles are congruent, which means that they have the same measurementWhen you have 2 lines that are parallel, which means that they are always equal distance from one another and never meet, and those lines are bisected by another line, then the angles in the top parallel line are equal to the angles in the bottom parallel line.
