1.

Let PQ be the latus rectum of the parabola `y^2 = 4x` with vetex A. Minimum length of the projection of PQ on a tangent drawn in portion of Parabola PAQ isA. `sqrt(2)a`B. `2asqrt(2)`C. `2a`D. `3asqrt(2)`

Answer» Correct Answer - B
Let tangent at `P(at^(2),2at)` make an angle `theta` with x-axis.
Then `tan theta = (1)/(t)`
Projection of BC on tangent
`= BC sin theta = (4a)/(sqrt(1+t^(2))) ge 2a sqrt(2) (as -1 le t le 1)`


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