Problem 506:
Given a point $H_{a}$, a point $H_{b}$ and a point $H$, construct the triangle ABC.

Construction: 
1. Using the point $H_{a}$ and the point $H$, construct a line $h_{a}$ (rule W02);
2. Using the point $H_{b}$ and the point $H$, construct a line $h_{b}$ (rule W02);
3. Using the point $H_{a}$ and the line $h_{a}$, construct a line $a$ (rule W10a);
4. Using the line $a$ and the line $h_{b}$, construct a point $B$ (rule W03);
5. Using the point $H_{b}$ and the line $h_{b}$, construct a line $b$ (rule W10a);
6. Using the line $b$ and the line $h_{a}$, construct a point $A$ (rule W03);
7. Using the line $a$ and the line $b$, construct a point $C$ (rule W03);
8. Using the point $B$ and the point $C$ construct the line $\_a$ (rule W02);
9. Using the point $A$ and the line $\_a$ construct the line $\_h_{a}$ (rule W10b);
10. Using the line $\_a$ and the line $\_h_{a}$ construct the point $\_H_{a}$ (rule W03);
11. Using the point $A$ and the point $C$ construct the line $\_b$ (rule W02);
12. Using the point $B$ and the line $\_b$ construct the line $\_h_{b}$ (rule W10b);
13. Using the line $\_b$ and the line $\_h_{b}$ construct the point $\_H_{b}$ (rule W03);
14. Using the line $\_h_{a}$ and the line $\_h_{b}$ construct the point $\_H$ (rule W03);

Statement:
Prove that the point $H$ is identical to the point $\_H$.

