
Start with the given segment lengths for the two legs L1 and L2 

1 
Draw a long horizontal line 

2 
Mark a point C somewhere near the middle of that line. 

3 
Set the compass width to the length of one of the given legs. (Here L1). 

4 
With the compasses on C, mark an arc on each side of C, creating points P and A 

5 
Increase the compass width by about 25% and with the compasses on P, make an arc above the point C 

6 
With the same compass width, and with the compasses on A, make another arc above C 

7 
Draw a line from C through the point where the arcs intersect. 

8 
Set the compass width to the length of the other given leg (here L2) 

9 
With the compasses on C, draw an arc above C across the line, creating point B. 

10 
Using the straight edge, draw the line AB 


Done. ABC is a right triangle with the given leg lengths 
