JEE MAIN - Mathematics (2022 - 28th June Evening Shift - No. 15)
If vertex of a parabola is (2, $$-$$1) and the equation of its directrix is 4x $$-$$ 3y = 21, then the length of its latus rectum is :
2
8
12
16
Explanation
Vertex of Parabola : (2, $$-$$1)
and directrix : 4x $$-$$ 3y = 21
Distance of vertex from the directrix
$$a = \left| {{{8 + 3 - 21} \over {\sqrt {25} }}} \right| = 2$$
$$\therefore$$ length of latus rectum = 4a = 8
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