Home
Class 12
MATHS
The distance between the directrix is eq...

The distance between the directrix is equal to 8 times the distance between the foci then e =

A

`1/2`

B

`(1)/(2sqrt(2))`

C

`1/4`

D

`1/8`

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the eccentricity \( e \) of the ellipse given that the distance between the directrices is equal to 8 times the distance between the foci. ### Step-by-step Solution: 1. **Understand the Relationships**: - The distance between the directrices of an ellipse is given by the formula: \[ \text{Distance between directrices} = \frac{2A}{e} \] - The distance between the foci of an ellipse is given by: \[ \text{Distance between foci} = 2Ae \] 2. **Set Up the Equation**: - According to the problem, the distance between the directrices is equal to 8 times the distance between the foci. Therefore, we can set up the equation: \[ \frac{2A}{e} = 8 \times (2Ae) \] 3. **Simplify the Equation**: - Simplifying the right side: \[ \frac{2A}{e} = 16Ae \] - Now, we can eliminate \( 2A \) from both sides (assuming \( A \neq 0 \)): \[ \frac{1}{e} = 8e \] 4. **Multiply Both Sides by \( e \)**: - To eliminate the fraction, multiply both sides by \( e \): \[ 1 = 8e^2 \] 5. **Solve for \( e^2 \)**: - Rearranging gives: \[ e^2 = \frac{1}{8} \] 6. **Find \( e \)**: - Taking the square root of both sides: \[ e = \sqrt{\frac{1}{8}} = \frac{1}{\sqrt{8}} = \frac{1}{2\sqrt{2}} \] ### Final Answer: Thus, the eccentricity \( e \) is: \[ e = \frac{1}{2\sqrt{2}} \]
Promotional Banner

Similar Questions

Explore conceptually related problems

If the distance between the directrices is thrice the distance between the foci, then find eccentricity of the ellipse.

In an ellipse the distance between the foci is 8 and the distance between the directrices is 25, then the ratio of the length of major and minor axis is

In a slide show programme, the image on the screen has an area 900times that of the slide. If the distance between the slide and the screen is x times the distance between the slide and the projector lens, then

The distance between the genes is measuredby

Prove that the distance between the origin and the point (-6, -8) is twice the distance between the points (4, 0) and (0, 3).

In an ellipse the distance between the foci is 8 and the distance between the directrices is 25. The length of major axis, is

Find the equation of an ellipse the distance between the foci is 8 units and the distance between the directrices is 18 units.

In an ellipse the distance between the foci is 8 and the distance between the directrices is 25. The length of major axis is : (A) 5sqrt(2) (B) 10sqrt(2) (C) 20sqrt(2) (D) none of these

The adjacent sides of a parallelogram are 10 m and 8 m. If the distance between the longer sides is 4 m, find the distance between the shorter sides.

If the distance between foci of a hyperbola is twice the distance between its directrices, then the eccentricity of conjugate hyperbola is :