Exercise 8 Page 653

Let's first explain the four steps in words:

1. Draw what's to be the first side of the triangle.
2. Draw an arc with a radius of AB and midpoint A.
3. Draw a second arc with a radius of AB and midpoint B.
4. Draw the triangles second and third side starting from A and B respectively and ending at the intersection of the arcs.

Since the two arcs are drawn with the same radius, AB, where they intersect is where we can draw the second and third side so they have the same length.