JEE MainMathematicsParabolaMCQ+4 / −1
A parabola has the origin as its focus and the line as the directrix. Then the vertex of the parabola is at :
- A
- B
- C
- D
View written solutionFree
Correct answer: B
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Given data
- Focus of the parabola: origin
- Directrix: line
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Key fact about a parabola The vertex lies midway between the focus and the directrix, measured along the axis perpendicular to the directrix.
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Find the axis Since the directrix is the vertical line , the axis of the parabola is horizontal. It must pass through the focus , so the axis is:
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Find the foot of the perpendicular from the focus to the directrix From to the line , the perpendicular meets the directrix at:
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Vertex is the midpoint The vertex is the midpoint of and :
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Match with options So the correct option is B.
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Comparison with stored answer Stored correct answer: B
Our derived answer is also B, so they agree.
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