16581on PERSPECTIVE.
the given Lines;
and conſequently L, or 1113, 14.
will be the Accidental Point ſought.
Prob. IV.
99.
To find the Repreſentation of one or more
Lines inclined to the Geometrical Plane.
Lines inclined to the Geometrical Plane.
Let a b be the Perſpective of the Direction of
22Fig. 56. the given Line: Now the Length of its Directi-
on may be determin’d, by means of the Tri-
angle ECP, according to the Directions of n. 69.
This being done, the Line b X muſt be drawn
through the Point b, equal to E P, and this re-
preſents a Perpendicular to the Geometrical
Plane; then a X being drawn, will be the Re-
preſentation ſought.
22Fig. 56. the given Line: Now the Length of its Directi-
on may be determin’d, by means of the Tri-
angle ECP, according to the Directions of n. 69.
This being done, the Line b X muſt be drawn
through the Point b, equal to E P, and this re-
preſents a Perpendicular to the Geometrical
Plane; then a X being drawn, will be the Re-
preſentation ſought.
Method II.
100.
To ſolve the ſame Problem by means of the
accidental Points F and T, the one being that of the
Lines propoſed; and the other, that of the Perpen-
33Fig. 56. diculars to the Geometrical Plane.
accidental Points F and T, the one being that of the
Lines propoſed; and the other, that of the Perpen-
33Fig. 56. diculars to the Geometrical Plane.
Operation.
Draw a Line from the Point F through the
Point a, which interſect in the Point X, by ano-
ther Line drawn from the Point T through b:
and then a X will be the Perſpective ſought.
Point a, which interſect in the Point X, by ano-
ther Line drawn from the Point T through b:
and then a X will be the Perſpective ſought.
Method III.
101.
The ſame Things being given as in the
44Fig. 101. aforegoing Method, draw a I through the Point
a, equal to E P, repreſenting a Line perpendicu-
lar to the Geometrical Plane. Then draw a pa-
rallel to F T through the Point I, whoſe
44Fig. 101. aforegoing Method, draw a I through the Point
a, equal to E P, repreſenting a Line perpendicu-
lar to the Geometrical Plane. Then draw a pa-
rallel to F T through the Point I, whoſe