...to a circle is always perpendicular to the radius passing through the point of contact. 31. To find the locus of the middle points of a system of parallel chords. Let PP' be one of the chords ; «f, y' the coordinates of P ; and x", y" those of P'. f. The equation...

...— 90, 92, 100 may be slightly altered so as to suit the parabola.) 113. A diameter of a curve is the locus of the middle points of a system of parallel chords. For example, in the circle a diameter is, according to this definition, a straight line drawn through...

...(SpQp— l)Sa<f>a — (Sp>pa)1 = 0. 254. To study the nature of the surface more closely, let us f'nd the locus of the middle points of a system of parallel chords. Let them be parallel to a, then, if sr be the vector of the middle point of one of them, w+xa and tsr—xa....

...— 90, 92, 100 may be slightly altered so as to suit the parabola.) 113. A diameter of a curve is the locus of the middle points of a system of parallel chords. For example, in the circle a diameter is, according to this definition, a straight line drawn through...

...by tangent lines parallel to a is 254. To study the nature of the surface more closely, let us find the locus of the middle points of a system of parallel chords. Let them be parallel to a, then, if is be the vector of the middle point of one of them, w+xa and *s—xa....

...that — Cos i(A+B) Cos?= Cos l(a+i)Sin2 • -, mm 2 Cos i(AB) Sin|= Sin l(a+i)Sin° (lg } e. Prove that the locus of the middle points of a system of parallel chords of a parabola is a straight line which meets the parabola in one point only. (10.) f. Find the equation...

...article contains a proof of the theorem which includes all the three cases. 177. PROP. II. To find the locus of the middle points of a system of parallel chords. Let P'P one of the chords be produced to meet the directrix in F, draw Ax parallel to FP, and divide...

...number of parallel chords all lie in the same diameter perpendicular to the chords. In other words, the locus of the middle points of a system of parallel chords is the diameter perpendicular to these chords. PROPOSITION VIII.— THEOREM. 18. In the same circle, or...

...number of parallel chords all lie in the same diameter perpendicular to the chords. In other words, the locus of the middle points of a system of parallel chords is the diameter perpendicular to these chords. PROPOSITION VIII.— THEOREM. 18. In the same circle, or...

...is therefore the area required. 81. It can be shewn by an investigation similar to that in Art. 71, that the locus of the middle points of a system of parallel chords of the surface By'+Cz' = x, whose direction-cosines are l, m, n, is Also the equation of the surface,...