diameter of the circle equals the top leg. Divide the diameter
into 3 equal parts. Then draw perpendicular line segments up to
meet the circle. Two more line segments connect these intersections
with the right vertex of the original triangle.
intersections of the 2 large circles with the diameter of the
smallest circle provide the points needed to mark off the top
leg of the triangle.
The complete construction for the original problem
is shown here.