MathematicsEasy74×since 2004Q3743A focus of an ellipse is at the origin. The directrix is the line x=4x=4x=4 and the eccentricity is 12{{1 \over 2}}21. Then the length of the semi-major axis is :A83{{8 \over 3}}38B23{{2 \over 3}}32C43{{4 \over 3}}34D53{{5 \over 3}}35Check answerSkip