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Figure 5.14
5.6 METHOD OF SUPERPOSITION
Traces are particular case of the principal lines of a plane, therefore this method is particular
case of previous method (rotation about the principal lines of a plane).
This method is superposition of given plane on horizontal or frontal plane of projection by
rotation about a horizontal or frontal trace of given plane respectively (Fig. 5.15). Plane α(α 1, α 2) is
given. To rotate any point N(N 1, N 2) of frontal trace about horizontal trace α 1 as an axis until it lies
in the horizontal plane of projection Π 1. Plane δ of rotation of point N is perpendicular to horizontal
trace (δ 1 is perpendicular to α 1). The path of rotation is a circle. In the horizontal plane of projection
(top view), this circle projects as a straight line perpendicular to α 1, with its center at O(O 1, O 2).
Point N 0 lies in the horizontal plane of projection at the point in which the circle cuts Π 1. Distance
from N 0 to α x and distance from α x to N 2 are equal (in space and on sketch).
Figure 5.15
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