The Elements of Perspective / arranged for the use of schools and intended to be read in connection with the first three books of Euclid

by John Ruskin

T V, are similar, and their angles are alternate;

But

a d

is parallel to A B—

∴ T V is parallel to A B.

[p101]
]II.

THE THIRD COROLLARY, PROBLEM III.

In [Fig. 13.], since

a

R is by construction parallel to A B in [Fig. 12.], and T V is by construction in [Problem III.] also parallel to A B—