MCQ
The points $(at_1^2,2a{t_1}),(at_2^2,2a{t_2})$and $(a,0)$will be collinear, if
  • A
    ${t_1}{t_2} = 1$
  • ${t_1}{t_2} = - 1$
  • C
    ${t_1} + {t_2} = 1$
  • D
    ${t_1} + {t_2} = - 1$

Answer

Correct option: B.
${t_1}{t_2} = - 1$
b
(b)$\frac{{a - at_2^2}}{{at_2^2 - at_1^2}} = \frac{{ - 2a{t_2}}}{{2a{t_2} - 2a{t_1}}}$
==> $(1 - t_2^2) = - {t_2}({t_2} + {t_1})$or ${t_1}{t_2} = - 1$.

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