Intersecting Lines:
Two lines that cross each other. Lines intersect at one point unless the lines fall directly on top of each other (in which case they are essentially the same line and are sometimes called coincidental).

Slopes and Angles of Elevation: Determine the relationship between the slope of a line and the angle the line makes with a horizontal line.

Comparing Lines: Examine the relationship between the coefficients in two linear functions if they are parallel, perpendicular, share the same intercept, and more.