JEE Math Practice Question
A focus of an ellipse is at the origin. The directrix is the line $$x=4$$ and the eccentricity is $${{1 \over 2}}$$. Then the length of the semi-major axis is :
- A.$${{8 \over 3}}$$
- B.$${{2 \over 3}}$$
- C.$${{4 \over 3}}$$
- D.$${{5 \over 3}}$$
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