1.

The sum of the squares of the distances of amoving point from two fixed points (a,0) and `(-a ,0)`is equal toa constant quantity `2c^2dot`Find theequation to its locus.

Answer» Let `P(h,k)` be any position of the moveing point and let `A(a,0), B(-a,0)` be the given points. Then, we have `PA^2+PB^2=2c^2` (Given)
or `(h-a)^2+(k-0)^2+(h+a)^2+(k-0)^2=2c^2`
`2h^(2)2k^2+2a^2=2c^2`
or `h^2+k^2=c^2-a^2`
Hence, the equation to locus `(h,k)` is `x^2+y^2 =c^2-a^2`.


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