A treatise on spherical trigonometry, and its application to geodesy and astronomy, with numerous examples. By John Casey.

8 Spherical Geometry. chord PD, describe the circle DEF. To describe a great circle, it is necessary that the opening of the compass should be equal to the chord of a quadrant. We can also, by the compass, divide an angle into 2, 4, 8, &c., equal parts, erect an arc of a great circle perpendicular to another, make a spherical angle equal to a given spherical angle, describe a circle touching three given circles, &c. ExEnCISES.-I. 1. A great circle passing through the poles of two others cuts each at right angles, and their points of intersection are its poles. 2-5. Solve the following problems with the compass:1~. Describe a great circle through two given points of the sphere. 2~. Through a given point of the sphere draw an arc of a great circle perpendicular to a given great circle. 3~. Make, at a given point of a given great circle, an angle equal to a given angle on the same sphere. 4~. Through a given point not on a given great circle draw a great circle making a given angle with it. 6. The loci of the poles of great circles, making a given angle a with a given great circle, consist of two small circles, having the same poles as the given circle. 7. The tangents at a given point A of the sphere to all circles (great or small) passing through A lie in the plane through A, perpendicular to the radius of the sphere drawn to that point. 8. If a tangent line to a sphere passes through a given point, the locus of the point of contact is a small circle. 9. If tangent lines to a sphere be parallel to a given line, the locus of the points of contact is a great circle. 10. The arc of a great circle, perpendicular to the spherical radius of a small circle at its extremity, touches the small circle. 11. Draw a great circle, touching two small circles. 12. Draw a great circle through a given point, touching a given small circle.

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Title
A treatise on spherical trigonometry, and its application to geodesy and astronomy, with numerous examples. By John Casey.
Author
Casey, John, 1820-1891.
Canvas
Page 2
Publication
Dublin,: Hodges, Figgis, & co.; [etc., etc.]
1889.
Subject terms
Spherical trigonometry.

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"A treatise on spherical trigonometry, and its application to geodesy and astronomy, with numerous examples. By John Casey." In the digital collection University of Michigan Historical Math Collection. https://name.umdl.umich.edu/abn7420.0001.001. University of Michigan Library Digital Collections. Accessed May 15, 2025.
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