A primary astronomy .. . , if extended outward to theheavens, or to infinity, are in the plane of the sheet, or the circle upon which it is point is in a plane produced, when the plane continued or extended would passthrough that point.] /i * PERPENDICULAR PLANES. S3. When are Planes said to be Parallel ? When so placed that they would never meetor cut each other, however far they might be ex-tended. [The two sides of a board, or two sheets of tin placed equidistant fromeach other at every point, represent parallel planes.] 34. When are Planes said to bePerpendicular 1 When one stands e
A primary astronomy .. . , if extended outward to theheavens, or to infinity, are in the plane of the sheet, or the circle upon which it is point is in a plane produced, when the plane continued or extended would passthrough that point.] /i * PERPENDICULAR PLANES. S3. When are Planes said to be Parallel ? When so placed that they would never meetor cut each other, however far they might be ex-tended. [The two sides of a board, or two sheets of tin placed equidistant fromeach other at every point, represent parallel planes.] 34. When are Planes said to bePerpendicular 1 When one stands exactly up-right upon the other; or whenthey cut each other at rightangles. [In the figure one plane is placed horizontally,and the other perpendicular to it. They aretherefore perpendicular to each other, howeverthey may stand in relation to the observer.] 35. When are Planes said to be In-clined 1 When they intersect or cuteach other obliquely. 36. What is meant by the Angle ofInclination 1 It is the angle contained be-. * A plane surface is to be distinguished from a pic 16 PRIMARY ASTRONOMY. ANGLE OF INCLINATION.
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectastronomy, bookyear18
