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If the base of a triangle and the ratio of the lengths of the other two unequal sides are given, then the vertex lies onA. straight lineB. circleC. ellipseD. parabola

Answer» Correct Answer - B
Let the base of the triangle be the line segment joining B(0, 0) and C(a, 0) and let the vertex be A(h, k), where a is fixed. Also, let
`(AB)/(AC)=lambda, lambda !=1`
`rArr AB^(2)=lambda^(2)AC^(2)`
`rArrh^(2)+k^(2)=lambda^(2){(h-a)^(2)+k^(2)}`
`rArr h^(2)(1-lambda^(2))+k^(2)(1-lambda^(2))+2a lambda^(2)h-a^(2)lambda^(2)=0`
So, A(h, k) lies on
`x^(2)+y^(2)+2a(lambda^(2))/(1-lambda^(2))x-(a^(2)lambda^(2))/(1-lambda^(2))=0`, which is a circle.


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