How to write an equation for the coordinate planes or any plane that is parallel to one.
How to find a vector normal (perpendicular) to a plane given an equation for the plane.
How to identify parallel lines, a line parallel to a plane, and two parallel planes.
How to plot complex numbers on the complex plane.
How to find the angle between planes, and how to determine if two planes are parallel or perpendicular.
How to define a tangent line; how to determine the angle a radius to a tangent forms.
How to define the tangent function for all angles.
How to evaluate the tangent of 3*pi/4.
How to find the length of tangent segments drawn to a circle from the same point.
How to describe and label point, line, and plane. How to define coplanar and collinear.
How to restrict the domain of tangent so it will have an inverse function.
How to define the tangent ratio and identify the tangent of an angle in a right triangle.
How to graph y = tan(theta) for 0 <= theta < pi/2.