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Question

Question: If ![](https://cdn.pureessence.tech/canvas_213.png?top_left_x=300&top_left_y=1675&width=300&height=4...

If then A =

A

xyx - y

B

x+yx + y

C

xy1+xy\frac { x - y } { 1 + x y }

D

x+y1xy\frac { x + y } { 1 - x y }

Answer

xy1+xy\frac { x - y } { 1 + x y }

Explanation

Solution

Given that tan1xtan1y=tan1A\tan ^ { - 1 } x - \tan ^ { - 1 } y = \tan ^ { - 1 } A

tan1(xy1+xy)=tan1A\Rightarrow \tan ^ { - 1 } \left( \frac { x - y } { 1 + x y } \right) = \tan ^ { - 1 } A.

Hence A=xy1+xyA = \frac { x - y } { 1 + x y }.