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Two points P(a,0) and Q(-a,0) are given, R is a variable on one side of the line PQ such that `/_RPQ-/_RQP` is a positive constant `2alpha`. FInd the locus of point R. |
Answer» `/_RPQ=phi` `/_RQP=theta` `phi-theta=2alpha` `tan(phi-theta)=2alpha` `(tanphi-tantheta)/(1+tanthetatanphi)=tan2alpha` `tantheta=y/(x+a),tanphi=y/(a-x)` `(y/(x+a)+y/(x-a))/(1-y^2/((x-a)(x-b)))=tan2alpha` `(2xy)/(a^2-x^2+y^2)=tan2alpha`. |
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