Difference between revisions of ".MzE1OA.Mjc1Mzg"
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Thro'. any given point F, to describe | Thro'. any given point F, to describe | ||
an Elipse about any given transverse | an Elipse about any given transverse | ||
− | [[note]] Fig. 1. [[ | + | [[note]] Fig. 1. [[/note]] Diameter. |
Apply the Eliptic compass, as before to the | Apply the Eliptic compass, as before to the |
Revision as of 09:04, 2 April 2020
the compass, & describe the other half.
Problem. 2.
Thro'. any given point F, to describe an Elipse about any given transverse note Fig. 1. /note Diameter.
Apply the Eliptic compass, as before to the given line AB. & adjust the Ink point to A. then fix the Beam by the conjugate Screw. & turn it over the given point F, Sliding it Untill the pen Coincides with F. then as in Problem 1. describe the Elipse. ACBD.
Problem. 3.
From a given point, k, without a Circle. ADBE. To draw two - Tangents & find their Chord. note Fig. 2. /note From O, the center of the Circle draw kO. & bisect it in f, then on center f. with Radius fO, describe the Arc. d, O, e, cutting the Circle in d, & e, draw kd, & ke, which will be tangents to the given circle from the point k. also draw de, thro the points of contact, & de, is the Required Chord.
Demonstration.
Draw Od, Oe, Then because kO, is the diameter of the Circle k, d, O, e, (fO being its Radius).