How to mark parallel lines, how to show lines are parallel, and how to compare skew and parallel lines.
How to determine whether two lines in space are parallel or perpendicular.
How to identify parallel lines, a line parallel to a plane, and two parallel planes.
How to take the converse of the parallel lines theorem.
How to find the vector and parametric equations of a line when given two points on the line.
How to find the angle of inclination of a line.
How to write the vector equation of a line.
How to find the polar equation of a line through the origin (or pole).
How to write the parametric equations of a line segment that goes from point A to point B.
How to write equations describing motion in a straight line given the velocity and the position when t=0.
How to plot complex numbers on the complex plane.
How to compute and simplify the difference quotient of a linear function.
How the number e is defined.
How to understand what vectors are, and how they can be represented geometrically.
How to convert a polar equation into rectangular form.