1.

A point moves so that the sum of its distances from `(a e ,0)a n d(-a e ,0)`is `2a ,`prove that the equation to its locus is `(x^2)/(a^2)+(y^2)/(b^2)=1`, where `b^2=a^2(1-e^2)dot`

Answer» AP+BP=2h
`AP=sqrt((h-he)^2+k^2)`
`BP=sqrt((h+he)^2+k^2`
`AP+BP=2h`
`(AP+BP)^2=4a^2`
`AP^2+BP^2+2(AP)(BP)=4a^2`
`(h-ae)^2+k^2+(h+ae)^2+k^2+2sqrt(((h-ae)^2+k^2)(h+ae)^2+k^2`
`h^2/a^2+k^2/b^2=1`
Putting h=x,k=y
`x^2/a^2+y^2/b^2=1`.


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