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

O a given ſtraight line () to apply a parallelogram gram equal to a given triangle (), and having an angle equal to a given reƈtilinear angle ().

Make $=$ with $=$ (pr. 42.)

and having one of its ſides conterminous

with and in continuation of .

Produce till it meets $\parallel$

draw produce it till if meets continued ;

draw $\parallel$ meeting

produced, and produce .

$=$ (pr. 43)

but $=$ (conſt.)

$\therefore$ $=$ and

$=$ $=$ $=$ (pr. 19. and conſt.)

Q. E. D.