how PS.ST=QS.SR?
5 Answers
AKHIL
·2011-04-04 05:04:35
its a JEE 2008 quesn !!!
oofff............JEE 2008 was really very hard man!!!:(
(PS) (ST) = (QS) (SR)
now use AM > GM
1/2 ( 1/PS + 1/ST ) > 1/ √(PS) (ST)
1/PS + 1/ST > 2/√(QS) (SR)
now if x+ y = k (a constant ) , then xy is max. when x = y = k/2
thus (QS ) (SR) < 1/4 (QR)2
1/(QS ) (SR) > 4/(QR)2
thus , 1/PS + 1/PT > 2√ 4/(QR)2 = 4/QR
so B and D r correct..
Joydoot ghatak
·2011-04-04 07:00:32
apply, similarity in triangle PSQ and TSR.
angle PQS = angle STQ
and angle PSQ = angle TSR.
thus,
triangle PSQ and TSR are similar
thus, PSSR = QSST.