... is the foot of the perpendicular from the point to the plane The projection of any figure on a plane is the locus of the projections of all points of the figure on the plane Thus, B is the projection ... side of a triangle and h the altitude on it and b another side and k the altitude on it, then ah = bk 62 The area of a trapezoid is equal to one half the product of its altitude and the sum of ... 214 SOLID GEOMETRY WITH PROBLEMS AND APPLICATIONS REVISED EDITION BY H E SLAUGHT, Ph.D., Sc.D PROFESSOR OF MATHEMATICS IN THE UNIVERSITY OF CHICAGO AND N J LENNES, Ph.D PROFESSOR OF MATHEMATICS...