Question

If the distance from a fixed straight line is 5mm and the distance from a fixed point is 14mm then what is the name of the conic section?

(a) Hyperbola

(b) Parabola

(c) Ellipse

(d) Circle

I had been asked this question by my school principal while I was bunking the class.

Question is from Basics of Conic Sections in section Curves used in Engineering Practice of Engineering Drawing

Answer 1

Correct option is (a) Hyperbola

The best explanation: The fixed straight line is called 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. The eccentricity of a hyperbola is greater than one.