How do we construct the basic geometric figures?

The geometric figure that were constructing is an equilateral triangle.
We are making  an equilateral triangle with a compass.

1. Start with the line segment. 
2. Put the needle of your compass at A and draw an arc.
3. Put the needle of your compass at B and draw an arc.
4. Draw the segments from the two endpoints to the point where the two arcs intersects.     

  

You should end with this :

• http://strader.cehd.tamu.edu/Mathematics/Geometry/PolygonLesson/Details/line_segment.html
• http://www.astarmathsandphysics.com/gcse_maths_notes/gcse_maths_notes_constructing_an_equilateral_triangle_60_degree_angle.html

HOW DO WE CONSTRUCT AN ISOSCELES TRIANGLE?