MR-827. problem

Determine the set (geometric position) of all points in the plane for which the distance ratio from the point F(3,0) and from the line v: 3x-4=0 is 3:2!

The line v is vertical and intersects the x-axis at 43.

Let's mark the required points with P(x,y)

Since line v is vertical, the distance of point P from line v is the horizontal distance. This distance determines the point V.

The x coordinate of point V is always 43

On the basis of the task, you can write:

PF¯:PV¯=3:2

Since we are actually looking for the distance of the points, it is best to square the expression.

PF¯2:PV¯2=9:4

9·PV¯2=4·PF¯2

PF¯2=x-32+y-02

PF¯2=x2-2·x·3+9+y2

PF¯2=x2-6x+9+y2

PV¯2=x-432+y-y2

PV¯2=x-432

PV¯2=x2-2·x·43+432

PV¯2=x2-83x+169

9x2-83x+169=4x2-6x+9+y2

9x2-24x+16=4x2-24x+36+4y2

9x2-4x2-4y2=36-16

5x2-4y2=20

5x2-4y2=20 |·120

5x220-4y220=1

x24-y25=1