BOOK I. PROP. XXXVI. THEOR.
37
ARALLELOGRAMS (
and 
) on equal bases, and between the same parallels, are equal.
Draw 
and 
,
= 
= 
, by (pr. 34, and hyp.);
∴ = and || ;
∴ = and || (pr. 33.)
And therefore 
is a parallelogram:
but = = (pr. 35.)
∴ = (ax. 1.).
Q. E. D.
