Group+C


 * Perpendicular Lines**

The picture to the far right is a set of perpendicular lines. The picture to the left is not a set of perpendicular lines.


 * Definition: If two lines intersect and create 90 degree angles, then the lines are a set of perpendicular lines.**




 * Definition: If they are formed by intersecting lines, are opposite of each other, and have equal degree measures, then they are vertical angles.**




 * Definition: If two lines intersect, and the angles next to each other on the same side are supplementary, then they are a linear pair of angles.**