Next, to find the dividing-point of the inclined line.
I remove some unnecessary lines from [the last figure] and repeat it here, [Fig. 77.], adding the measuring-line
a
M, that the student may observe its position with respect to the other lines before I remove any more of them.
Now if the line A B in this diagram represented the length of the line A B in reality (as A B does in [Figs. 10.] and [11.]), we should only have to proceed to modify [Corollary III.] of [Problem II.] to this new construction. We shall see presently that A B does not represent the actual length of the inclined line A B in nature, nevertheless we shall first proceed as if it did, and modify our result afterwards.
[p105]
]In [Fig. 77.] draw
a d
parallel to A B, cutting B T in
d
.