`tan^(-1)x+tan^(-1)y=`................. ( if x>0,y>0 and xy<1)

Q.tan^(^^)-1x+tan^(^^)-1y=pi+tan^(^^)-1((x+y)/(1-xy)) if x,y>0 and xy>0Q*cos^(^^)-1x+cos^(^^)-1y=2pi-cos^(^^)-1(xy-sqrt(1-x^(^^)2)sqrt(1-y^(^^)2)) if x+y<0

If tan^(-1)x+tan^(-1)y=(pi)/(4) , and the value of xy<1 ,then show that x+y+xy=1 .

xy = tan (x + y)

If tan^(-1) x +tan^(-1) y = pi/4 , xy lt 1 , then prove that x+y+xy=1 .

If tan ^(-1) x + tan ^(-1) y + tan ^(-1) z = (pi)/(2), then xy + yz+zx is equal to

If tan^(-1) x + tan^(-1)y + tan^(-1)z = pi show that : 1/(xy) + 1/(yz) + 1/(zx) = 1