Please solve this?

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1 Answer
Apr 14, 2018

C) #5#

Explanation:

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Given #AB=AC, and angleADB=90^@#
#=> BD=DC#
#DeltaCHE, DeltaCAD, DeltaBAD and DeltaBFE# are all similar,
#=> (CE)/(HE)=(BE)/(FE), => (CE)/2=(BE)/8, => BE=4CE#,

Let #CE=a, => BE=4a, => BC=BE+EC=5a#,
#=> BD=DC=(BC)/2=(5a)/2#
#=> x/(BD)=(FE)/(BE)#
#=> x=BD*(FE)/(BE)=(5a)/2*8/(4a)=5#

Footnotes : #DeltaBAD and DeltaCAD# are actually congruent. :)