WBJEE · Maths · Parabola
\(\mathrm{AB}\) is a chord of a parabola \(\mathrm{y}^2=4 \mathrm{ax},(\mathrm{a}>0)\) with vertex \(\mathrm{A} . \mathrm{BC}\) is drawn perpendicular to \(\mathrm{AB}\) meeting the axis at \(\mathrm{C}\). The projection of \(\mathrm{BC}\) on the axis of the parabola is
- A a unit
- B 2a unit
- C 8a unit
- D 4a unit
Answer & Solution
Correct Answer
(D) 4a unit
Step-by-step Solution
Detailed explanation
\begin{aligned} &\mathrm{B}\left(a \mathrm{at}^2, 2 a t\right) \therefore \mathrm{D}\left(\mathrm{at}^2, 0\right) \\ &\mathrm{m}_{\mathrm{AB}}=\frac{2 a \mathrm{at}^2}{\mathrm{at}^2}=\frac{2}{\mathrm{t}} \therefore \mathrm{m}_{\mathrm{BC}}=-\frac{\mathrm{t}}{2} \end{aligned}…
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