Question

The line PQ is a focal cord of the ellipse x²/25 + y²/16 = 1 If the focus S = (3, 0) and SP = 2, then the length PQ is equal to 

(A)  8 

(B)   4 

(C)  10 

(D)   6

Answer 1

Correct option (C) 10 

Explanation :

Major axis length is 2 x 5 = 10. S = (3, 0) and SP = 2. Since the vertex A (see Fig.) is (5, 0), it follows that SA = 2 and A = P

Therefore, PQ is nothing but the major axis and hence PQ = 10.