Question: The length of the semi major axis of an ellipse is 3, the eccentricity is 0.3. What is the distance from a focus of the ellipse to the closer vertex?
A ) 0.9 B ) 3.9 C ) 2.1 D ) 2.7
Steps to derive
1 The length of the semi major axis of the ellipse is 3 and eccentricity is 0.3.
2 So, c = ae = (3)(0.3) = 0.9 [Replace a with 3 and e with 0.3.]
3 The distance form a focus to the closer vertex is the perihelion distance = a - c = 3 - 0.9 = 2.1.
