Q57 of 63 Page 202

The eccentricity of the hyperbola whose latus rectum is 8 and conjugate axis is equal to half of the distance between the foci is

Length of Latus Rectum =



b2 = 4a ------- (i)


As, Conjugate axis is equal to half of the distance between the foci,


2b = ae


Squaring the above mentioned equation,


4b2 = a2e2 -------- (ii)


b2 = a2 (1 - e2)


4a = a2 (1 - e2)


4 = a (1 - e2)


-------- (iii)


Putting the value from equation (ii),



a = 20


b2 = 4a = 4 × 20 = 80 {From equation (i)}




Hence, the eccentricity of hyperbola is .

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