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 240
ry point on a given straight line passes through thepole of that line. For the benefit of the learner I will give anotherproof of these principles in the next proposition. 240. If a point move along a fixed straight line, itspolar always passes through a fixed point, viz. the pole of iliefixed… … shall the polar of P pass through the pole of AB. From the centreC, draw CD perpendicular to AB, and let QR the polar of P meetCD (or CD produced) in R. Because the angles PDR and PQR are right, the four pointsP, Q, R, D lie on the same circumference, therefore PC .CQ = DC .CR, but PC. CQ equals…
Geometry
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