A short course in astronomy and the use of the globes (1871)
Kiddle, Henry, 1824-1891 · New York, Chicago, Ivison, Blakeman, Taylor & co. · leaf 14
18. What is the angle of vision ? Remark ? Illustrate hy diagram. 19. How isan angle measured? 20. What is a right angle? 21. A perpendicular? 22. A per-pendicular to a circle ? 23. What is an acute angle ? An obtuse angle ? ,IN TRODUCTION. U … In the annexed diagram, the semi-circumference is used to measure allthe angles having their vertices, orangular points, at C. Thus BCD,containing the arc B D, is an angle of45°; B C E, an angle of 90°; and B C F, Jof 120°. The points A and B are atthe angular distance of 180°, or two right angles…
Astronomy
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