Manning, Henry Parker, 1859- · Boston, U.S.A., Ginn & Company · leaf 64
d asan axis, and the surface is a surface cutting at right angles asystem of lines perpendicular to the plane. The surface hasa constant curvature, fitting upon itself in any position. III. TRIGONOMETRICAL FORMULA 1. Let ABC be a plane right triangle. Erect A A perpen-dicular to its plane and draw…
Geometry, Non-Euclidean
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