Exercises on Euclid and in modern geometry for the use of schools, private students, and junior university students (1881)
McDowell, James L · Cambridge, Deighton, Bell, and Co. · leaf 184
. Therefore the anhar-monic ratio of four fixed points on a circle is constant. 190. If a variable tangent meet two fixed tangents, theintercept on it subtends a constant angle at the centre of thecircle.
Geometry
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