Originally Posted by

**varunkanpur** I am not able to solve this problem-

Two fixed points A and B are taken on the axes such that

OA = a and OB = h; two variable points A' and B' are taken on the

same axes; find the locus of the intersection of AB' and A'B

(1) when OA' + OB' = OA + OB,

and (2) when 1/OA' - 1/OB' = 1/OA - 1/OB

What I was doing

OA' + OB' = a + b

a- OA' + b - OB' = 0

AA' + BB' = 0

AA'=-BB'

OA' = OA -AA'

= a + BB'

x/(a + BB') +y/b = 1 equation No. 1

OB' = OB - BB'

= b - BB'

x/(a) +y/(b-BB') = 1 equation No. 2

Solving 1 and 2 to eliminate BB' and get a relation of required locus.

But answer is of (i) x+y-a-b=0

(ii) y=x

Thanx in Advance.