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Question

Question: \(\cot ^ { - 1 } \frac { x y + 1 } { x - y } + \cot ^ { - 1 } \frac { y z + 1 } { y - z } + \cot ^ {...

cot1xy+1xy+cot1yz+1yz+cot1zx+1zx=\cot ^ { - 1 } \frac { x y + 1 } { x - y } + \cot ^ { - 1 } \frac { y z + 1 } { y - z } + \cot ^ { - 1 } \frac { z x + 1 } { z - x } =

A

0

B

1

C

cot1x+cot1y+cot1z\cot ^ { - 1 } x + \cot ^ { - 1 } y + \cot ^ { - 1 } z

D

None of these

Answer

0

Explanation

Solution

cot1xy+1xy+cot1yz+1yz+cot1zx+1zx\cot ^ { - 1 } \frac { x y + 1 } { x - y } + \cot ^ { - 1 } \frac { y z + 1 } { y - z } + \cot ^ { - 1 } \frac { z x + 1 } { z - x }

=cot1ycot1x+cot1zcot1y= \cot ^ { - 1 } y - \cot ^ { - 1 } x + \cot ^ { - 1 } z - \cot ^ { - 1 } y +cot1xcot1z=0+ \cot ^ { - 1 } x - \cot ^ { - 1 } z = 0.

Note: Students should remember this question as a formula.