Page:First six books of the elements of Euclid 1847 Byrne.djvu/36

2 ROM a given point, to draw a straight line equal to a given finite straight line.



Draw (post. 1.), describe  (pr. 1.), produce  (post. 2.), describe  (post. 3.), and  (post. 3.); produce  (post. 2.), then  is the line required.

For =  (def. 15.), and  =  (const.), ∴  =  (ax. 3.), but (def. 15.)  =  =  :

∴ drawn from the given point, is equal the given line.

Q.E.D.