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THere cannot be drawn from the same point Two Perpendiculars to a Plane.
If the Two Lines CD, CE, drawn from the same point C, were perpendi∣cular to the Plain AB; and that CE was the common section of the Plane of those Lines, with the Plane AB; the Angles
ECF, DCF, would be Right; which is impossible.
I further add, that there cannot be drawn from the same point D Two per∣pendiculars DC, DF, to the same Plane AB: for having drawn the Line CF, there will be made Two Right Angles DCF, DFC, in one Triangle contrary to the 32d. of the first.
THis Proposition is necessary to shew, that a Line which is drawn perpendi∣cular to a Plane is well determined, seeing there can be drawn but only one from a Point.