A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 231
h the centre and limited by the surface is a Diameter.The diameter is equal to twice the radius. * a epherical blackboard is almost indispensable in teaching this section, as well as inteaching Spherical Trigonometry. A sphere about 2 feet in diameter, mounted on a pedestal,and having its surface… … PROPOSITION L 533. Tlieorem.—Every section of a sphere, made hy a plane, tia circle. Dem.—Let AFEBD be a section of a sphere•whose centre is 0, made by a plane; then is it acircle. For, let fall from the centre O a pei-pendicularupon the plane AFEBD, as OC, and draw CA, CD,CE, CB, etc., lines of…
Geometry · Trigonometry
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