COROLLARY I.

As, if the point _b_ is first found, _V_ may be determined by it, so, if

the point _V_ is first found, _b_ may be determined by it. For let _AB_,

Fig. 10., be the given line, constructed upon the paper as in Fig. 8.;

and let it be required to draw the line _ab_ without using the point

_C′_.

[Illustration: Fig. 10.]

The Elements of Perspective arranged for the use of schools and intended to be read in connection with the first three books of Euclid · 第 18 / 91 题