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Appleton
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Homework Statement
A point P moves so that its distances from A(a, 0), A'(-a, 0), B(b, 0) B'(-b, 0) are related by the equation AP.PA'=BP.PB'. Show that the locus of P is a hyperbola and find the equations of its asymptotes.
Homework Equations
The Attempt at a Solution
AP.PA' = [itex]((a-x)\boldsymbol i + y\boldsymbol j).((-a-x)\boldsymbol i+y\boldsymbol j)[/itex]
AP.PA' = [itex]x^2-a^2+y^2[/itex]
BP.PB' = [itex]((b-x)\boldsymbol i + y\boldsymbol j).((-b-x)\boldsymbol i+y\boldsymbol j)[/itex]
BP.PB'= [itex]x^2-b^2+y^2[/itex]
So
[itex]a^2=b^2[/itex]
This result sugests that their is no constraint on P. This is not consistent with the question.
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