## An Elementary Treatise on Trilinear Co-ordinates: The Method of Reciprocal Polars, and the Theory of Projections |

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An Elementary Treatise on Trilinear Co-Ordinates, the Method of Reciprocal ... Norman MacLeod Ferrers No preview available - 2015 |

### Common terms and phrases

angular points anharmonic ratio appears asymptotes becomes called centre Chap CHAPTER chord circle circumscribing co-ordinates coincide common tangents condition conic conjugate considered constant curve described determine directrix distance drawn equal equation EXAMPLES expressed fixed point foci focus follows four points given conic given point given straight lines gives Hence identical imaginary inscribed internal line at infinity lines joining locus lying meet obtained opposite sides pair parabola parallel passing perpendicular points of contact points of intersection polar pole positive projection proposition prove range reciprocal rectangular hyperbola relation represented respect right angles satisfy second degree seen shew sides similar Similarly suppose taken tangents term theorem third three points three straight lines tion touch triangle of reference values whence written

### Popular passages

Page 110 - ... 8 right angles. 10. Represent the arithmetic, geometric, and harmonic means, between two given lines geometrically. 11. The centre of the circle circumscribed about any triangle, the point of intersection of the perpendiculars let fall from the angular points of the same triangle to the opposite sides, and the point of intersection of the lines joining the angular points with the middle of the opposite sides, all lie in the same right line. 12. If four circles touch each either internally or...

Page 118 - Prove that the locus of the point of intersection of the tangents at P, Q, is a straight line. Shew that this straight line passes through the intersection of the directrices of the conic sections, and that the sines of the angles which it makes with these lines are inversely proportional to the corresponding excentricities.

Page xiv - The plane curve described by a point which moves in such a manner that the sum of its distances from two fixed points (the foci) remains the same in all its positions.

Page 76 - In other words, if a rectangular hyperbola be so described that each angular point of a given triangle is the pole, with respect to it, of the opposite side, it will pass through the centres of the four circles which touch the three sides of the triangle.

Page 2 - To find the co-ordinates of the point of intersection of two given straight lines. Let the equations of the lines be ax + by +c = 0 (i), and a'x + b'y + c

Page 118 - OI/On, and On is constant and na fixed point. 2. Another proof is given as a problem in The Ancient and Modern Geometry of Conies, page 122 (1881), thus, " 279. If PQ be a chord of a conic which subtends a right angle at a given point...

Page 160 - Any straight line drawn from the vertex of a triangle to the base is bisected by the straight line which joins the middle points of the other sides of the triangle.

Page 114 - Let them be denoted by F and F' (fig. 72), and let the axis of x be taken through them, and the origin halfway between them. Then if P is any point on the ellipse and 2 a represents the constant sum of its distances from the foci, we have F'P+FP=2a.

Page 119 - ... subtends a right angle at a fixed point. Prove that the locus of the point of intersection of the variable tangents is a straight line.