Constructing Triangles

Date: 3/6/96 at 18:34:18
From: Gary Richey
Subject: Constructing 30-60-90 triangles

How do you construct 30-60-90 triangles with a compass and 
a straight edge?

Date: 6/25/96 at 15:16:25
From: Doctor Robert
Subject: Re: Constructing 30-60-90 triangles

It's not too difficult to do this. First you need to construct an 
equilateral triangle.  Start with a horizontal line segment.  
Set your compass to the length of this line and draw arcs, 
using this radius, from each end of the original segment.  
The point where they intersect and the endpoints of the 
original segment are the vertices of an equilateral triangle.

Now bisect one of the angles.  This bisector will intersect 
the opposite side and will form two 30-60-90 right triangles.  

-Doctor Robert,  The Math Forum