Analytic geometry and principles of algebra (1913)
Ziwet, Alexander, 1853-1928, Hopkins, Louis Allen, joint author, Hedrick, E. R. (Earle Raymond), 1876-1943 · New York, The Macmillan Company · leaf 233
Fig. 94 … Fig. Ito X, § 230] ELLIPSE AXD HYPERBOLA 221 230. Area of Ellipse. Since any ellipse of semi-axes a, hcan be regarded as the projection of a circle of radius a,inclined to the plane of the ellipse at an angle e such thatcos € = h/a, the area A of the ellipse is A = 7ra^ cos e = Tvah. vw .2^L.J.…
Geometry, Analytic
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