Page:First six books of the elements of Euclid 1847 Byrne.djvu/70

36 ARALLELOGRAMS on the same base, and between the same parallels, are (in area) equal. On account of the parallels,

= ; (pr. 29.)

= ; (pr. 20.)

and =  (pr. 34.)

But, =  (pr. 8.)

∴ minus  = ,

and minus  =

∴ =.

Q. E. D.