Find the equation of the locus of a point p (x, y) such that pv…

Find the equation of the locus of a point p (x, y) such that pv = pw, where v= (1, 1) and w = (3, 5)
  • A.
    2x + 2y = 9
  • B.
    2x + 3y = 8
  • C.
    2x + y = 9
  • D.
    x + 2y = 8
Correct Answer: Option D
Explanation

The locus of a point p(x, y) such that pv = pw where v = (1, 1)
and w = (3, 5). This means that the point p moves so that its distance from v and w are equidistance
(sqrt{(x − x_1)^2 + (y − y_1)^2}) = (sqrt{(x − x_2)^2 + (y − y_2)^2})
(sqrt{(x -1)^2 + (y – 1)^2}) = (sqrt{(x – 3)^2 + (y – 5)^2})
square both sides
(x – 1)2 + (y – 1)2 = (x – 3)2 + (y – 5)2
x2 – 2x + 1 + y2 – 2y + 1 = x2 – 6x + 9 + y2 – 10y + 25
x2 + y2 -2x -2y + 2 = x2 + y2 – 6x – 10y + 34
Collecting like terms
x2 – x2 + y2 – y2 – 2x + 6x -2y + 10y = 34 – 2
4x + 8y = 32
Divide through by 4
x + 2y = 8

There is an explanation video available below.

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