If tan (x + y) + tan (x – y) = 1, find.

We are given with an equation tan(x + y) + tan(x – y) = 1 , we have to find by using the given equation, so by differentiating the equation on both sides with respect to x, we get,


sec2(x + y)[1 + ] + sec2(x – y)[1 – ] = 0


[sec2(x + y) – sec2(x – y)] + sec2(x + y) + sec2(x – y) = 0



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