Test Index

NDA Math Conic Section

Question : 8 of 34

Marks: +1, -0

Consider the following with regard to eccentricity (e) of a conic section:

e=0

for circle

e=1

for parabola

e < 1

for ellipse

Which of the above statements is/are correct?

[NDA-I 2021]

1 and 2 only
2 and 3 only
1 and 3 only
1,2 and 3

Validate

Solution: 👈: Video Solution

CONCEPT:
Eccentricity:

The constant ratio of distance of point lying on conic from the focus to its perpendicular distance from directrix is called the eccentricity of a conic section and is denoted by e.

- For an ellipse:

e < 1

- For a parabola:

e=1

- For a hyperbola:

e > 1

- For a circle:

e=0

- For a pair of straight lines:

e=\infty

CALCULATION:

As we know that, eccentricity of a circle is 0 i.e

e=0

for a circle.

So, statement 1 is correct.

We also know that, eccentricity of a parabola is equal to 1 i.e e

=1

for a parabola.

So, statement 2 is also correct.

We also know that, eccentricity of an ellipse is always less than 1 i.e

e < 1

for an ellipse.

So, statement 3 is also correct.

Hence, correct option is

4.

Go to Question:

Prev Question

Next Question