Solution: First, from the right triangle whose vertices are (0,0), (0,2a), and (x,2a),
Second,let be the length of the line from (0,0) to A.
From the right triangle whose vertices are (0,0), D, and A
Third, from the right triangle whose vertices are (0,0), (0,2a), and A
Consequently
This is the witch:
by: gm