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

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.