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A focus of an ellipse is at the origin. The directrix is the line x=4 and the eccentricity is 1 / 2 . Then the length of the semi-major axis is

Options

  1. A8 3
  2. B2 3
  3. C4 3
  4. D5 3

Correct answer

A. 8 3

Step-by-step solution

Major axis is along x -axis. aligned & a e -a e=4 & a (2- 1 2 )=4 & a= 8 3 . aligned

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