eccentricity

Question

what is the eccentricity of:

x^2/9 + y^2/81 = 1 ?

(x+2)^2/36 + (y-4)^2/11 = 1?

Answer 1

Both of the figures are ellipses.

For an ellipse

e = √(a² - b²) / a

 

For the first equation

 

e = √(81 - 9) / 9

e = √72 / 9

e = 6√2 / 9

e = 2√2 / 3

 

Use the same formula for the second equation.