Constructing an isosceles triangle
Constructing an isosceles triangle also known as drawing an isosceles triangle using only a straightedge and a compass is what I will show you here
Take your ruler and a pencil and construct a segment of any length on a piece of paper as shown below
Then, you will open or close your compass opening to a distance bigger or smaller than segment AB
Take your compass. Make your sure that the pencil is included in it.
You may have to put one hand where the needle is and one hand where the pencil is.
Then open or close the compass making sure that the distance of the opening is bigger or smaller than the length of segment AB
For this situation, we will open the compass to a distance greater than segment AB
Put the needle of your compass at A and draw an arc
Put the needle of your compass at B and draw an arc
The two arcs should meet as shown below:
Draw the segments from the two endpoints to the point where the two arcs intersets