A new manual of the elements of astronomy, descriptive and mathematical .. (1868)
Kiddle, Henry, 1824-1891 · New York, Ivison, Phinney, Blakeman & co.; Chicago, S.C. Griggs & co. · leaf 18
^B In the annexed diagram, the semi-cir-cumference is used to measure all theangles having their vertices, or angularpoints, at C. Thus BCD, containingthe arc B D, is an angle of 45°; B C E,an angle of 90°; and BCF, of 120°.The points A and B are at the angulardistance of 180°, or two right… … Parallel Lines. Fig. 11. a. The sum of the three angles of every trian-gle is equal to two right angles. b. A triangle that contains a right angle iscalled a Right-angled Triangle. c. A triangle having equal sides is called anEquilateral Triangle. d. Each of the angles of an equilateral triangleis…
Astronomy
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