Manning, Henry Parker, 1859- · Boston, U.S.A., Ginn & Company · leaf 89
vertex A. Differentiating the equation sin A = where bis constant, we have cos Ad A = But or (II.) cosBcos$ sin BdBcosi5 cos A , sin B = cosm .. dB = — cosia cos ib dA, dB =— cos icdA. Now, using polar coordinates, we have an infinitesimal righttriangle whose hypothenuse, ds, makes an angle, say… … For two arcs cutting at right angles, let d denote differ-entiation along the second arc: sin ip d9 _ i dp i dp sinip dO dp dp or d6 dO = sur*p. 11. Area: It equals ff*?* We will consider only the case where the origin is withinthe area to be computed and where each radius vector meetsthe bounding…
Geometry, Non-Euclidean
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