A) $ \frac{h\cot x}{\cos x+\cot y} $
B) $ \frac{h\cot ,y}{\cos x+\cot y} $
C) $ \frac{h\cot ,x}{\cot x-\cot y} $
D) $ \frac{h\cot ,y}{\cot x-\cot y} $
Correct Answer: C
$ \Rightarrow $ $ \tan x=\frac{b-h}{ED} $
$ \Rightarrow $ $ ED=(b-h)\cot x $ (i) From $ \Delta ABC, $ $ \tan y=\frac{AB}{BC} $
$ \Rightarrow $ $ \tan y=\frac{b}{BC} $
$ \Rightarrow $ $ BC=b\cot y $ (ii) From Eqs. (i) and (ii), we get $ BC=ED $
$ \therefore $ $ (b-h)\cot x=b\cot y $
$ \Rightarrow $ $ b\cot x-h\cot x=b\cot y $
$ \Rightarrow $ $ b,(\cot x-\cot y)=h\cot x $
$ \therefore $ $ b=\frac{h\cot x}{\cot x-\cot y} $