...(Adapted from Fundamental Formulas of Physics DH Menzel, ed., Prentice-Hall, Inc., 1955) or Definition: the locus of a point which moves so that its distance from a fixed point (focus) bears a constant ratio e (eccentricity) to its distance from a fixed straight line (directrix)....

...directrix definition of a conic. I. The definition according to Maccullagh is as follows : The conicoid is the locus of a point which moves so that its distance from a fixed point is in a constant ratio to its distance from a given straight line measured parallel to a given plane....

...= 1 . # 143 LOCUS AND THE PARABOLA (A) The Parabola x 2 = 4 av (i) Locus A parabola is defined as a locus of a point which moves so that its distance from a fixed point (called the focus) is equal to its distance from a fixed straight line (called the directrix). This...

...and the line the directrix (see figure 2.26). Indeed, the parabola is more traditionally defined as the locus of a point which moves so that its distance from a fixed point is equal to its perpendicular distance from a fixed straight line. From this its equation is derived....

...axis. This is a fundamental property of the ellipse, which can be used as an alternative definition of the ellipse. The ellipse is the locus of a point which moves in a plane such that the sum of its distances from two fixed points on that plane is a constant. Note...

...given : it will be seen that the three curves are particular cases of what is called a Conic*. A Conic is the locus of a point which moves so that its distance from a fixed point (called the focus) bears a constant ratio to its distance from a fixed straight line called the directrix...

...the section extends indefinitely. The conic is then a 'parabola,' and A is its 'vertex.' A parabola is the locus of a point which moves so that its distance from a fixed point equals its distance from a fixed line. If the eccentricity is less than 1, then SA < AK. Hence AE<AK,...

...and Ix + my = I is a point (дг1, У) such that — / in anf - 2hlm + bP • [Circle] 1. A circle is the locus of a point which moves so that its distance from a fixed point, called the centre is equal to a given distance. The given distance is called the radius of the circle....

...simplification we get the required equation of the parabola. 26.8 PARABOLA Definition : A parabola is the locus of a point which moves so that its distance from a fixed point is equal to its distance from a fixed straight line. In case of parabola eccentricity is 1 Standard...

...¿. ¿ -¿.* ¿ - ¿ ¿ - ¿ ¿ • -¿1¿ ¿ . ¿ . ¿ . ¿ -a-' -‘¿- - 23. CIRCLES 1. A circle is the locus of a point which moves so that its distance from a fixed point is constant. The fixed point is called the centre of the circle and the constant distance is called...