Smith, David Eugene, 1860-1944 · Boston, New York [etc.] Ginn and Company · leaf 220
ill lie on a circle inclosing thedangerous area. Angle A is calledthe horizontal danger angle. Ships passing in sight of the twolighthouses L and L must keep out far enough so that the angleLSL shall be less than angle A. To this proposition there are several important corol-laries, including the… … 210 THE TEACHING OF GEOMETRY
Geometry
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