Question

If the distance from a fixed straight line is 5mm and the distance from a fixed point is 14mm then what is the value of eccentricity?

(a) 0.357

(b) 3.57

(c) 2.8

(d) 0.28

The question was asked in exam.

My doubt stems from Basics of Conic Sections topic in division Curves used in Engineering Practice of Engineering Drawing

Answer 1

Correct answer is (c) 2.8

The explanation: The fixed straight line is called as directrix and the fixed point is called as a focus. Eccentricity is defined as the ratio of the distance from the focus to the distance from the directrix and it is denoted by e. Hence from definition e = 14 ÷ 5 = 2.8.