3) Mark the center of the forward vertical beam at 2 locations.
point a1 on the table near the laser, and point a2 on the wall A.
4) Mark the center of the side vertical beam at 2 locations.
point b1 on the table near the laser, and point b2 on the wall B.
(see figure 10).
a2
X
A
9
# תמונה
X
X
a1
Figure # 10
B
X
b1
b2
21