If tan−1x+tan−1y=π4,xy<1. then write the value of x+y+xy.
We have tan−1x+tan−1y=π4, ⇒tan−1(x+y1−xy)=π4 ⇒x+y1−xy=tanπ4 ⇒x+y1−xy=1
∴ x+y+xy=1.
If tan−1x+tan−1y=π4 where xy < 1, find the value of x+y+xy.