Basic Constructions
In geometric constructions, you need only four instruments: paper, pencil, a ruler or straightedge, and a compass (instrument used to draw circles). The diagrams you see were all created using AutoCAD 2002. They are very self explanatory. A large circle represents a circle drawn by a compass. A point is usually a very small circle. Circles are referred to by their centers, so in this case, this circle is called circle O. A line is only allowed to connect given points or intersections. They will be represented by a pair of letters with a line above them. So, the line in this diagram is called line AB. 
Line Bisection The bisection of a line is one of the most fundamental of all geometric constructions. In this example, we construct the perpendicular bisector. Suppose you have line AB.

Angle Bisection This section shows you the procedure to bisect any arbitrary angle. That is, given an angle, cut it in half exactly. So, given angle AOB:

Perpendiculars We've seen how to contruct a perpendicular bisector. What if we want to construct a perpendicular line through any point? Given AB, we want to construct a perpendicular at point M:

Parallels
Suppose you want to construct a line parallel to a given line, through a given point. You would follow this procedure:

Mascheroni Bisection A Mascheroni construction does not use a straightedge, making the bisection of a line ten times harder! You are given two points A and B:
