Answers

2014-04-16T09:53:43+05:30
THIS IS A QUESTION ASKED IN IIT-JEE 
WE KNOW THAT sec^2(a)>=1
hence 4xy/(x+y)^2>=1
hence,4xy>=(x+y)^2
which gives (x-y)^2<=0
thus only equality will hold since a square term can't be zero
hence (x-y)=0 i.e.x=y
and x or y can't be zero because sec^2(a) can't be zero 

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