Page:First six books of the elements of Euclid 1847 Byrne.djvu/79

44 O a given straight line to apply a parallelogram gram equal to a given triangle , and having an angle equal to a given rectilinear angle. Make = with = (pr. 42.)

and having one of its fides conterminous

with and in continuation of.

Produce till it meets ∥

draw produce it till if meets continued ;

draw ∥ meeting

produced, and produce.

= (pr. 43)

but = (conft.)

∴ =  ; and

= = = (pr. 19. and const.)

Q. E. D.