Higbee, F. G · New York, John Wiley & Sons · leaf 86
ex of the required angle. Fromany other point N of NQ draw a Hne perpendicular to the plane PROBLEMS ON POINTS, LINES, AND PLANES 75 S and find where it pierces the plane S. This point is P,shown in plan at p and in elevation at p, and MP is theprojection of MN upon S. NMP, then, is the angle the… … Fig. 60. In the problem just solved it will be observed that since the angleMPN is a right angle — NP being perpendicular to MP — theangle PNM is the complement of the required angle. If, there-fore, from any point of the given line a perpendicular be drawnto the given plane the angle between the…
Geometry, Descriptive
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