Question:
If the points P (x, y) is equidistant from A (5, 1) and B (−1, 5), then
(a) 5x = y
(b) x = 5y
(c) 3x = 2y
(d) 2x = 3y
Solution:
It is given that $\mathrm{P}(x, y)$ is equidistant to the point $\mathrm{A}(5,1)$ and $\mathrm{B}(-1,5)$
So,
$\mathrm{PA}^{2}=\mathrm{PB}^{2}$
So apply distance formula to get the co-ordinates of the unknown value as,
$(x-5)^{2}+(y-1)^{2}=(x+1)^{2}+(y-5)^{2}$
On further simplification we get,
$25-10 x+1-2 y=1+2 x+25-10 y$
So,
$12 x=8 y$
Thus,
$3 x=2 y$
So the answer is (c)