If sin−1x+sin−1y+sin−1z=π then x4+y4+z4+4x2y2z2=k(x2y2+y2z2+z2x2) where k is equal to
2
sin−1x+sin−1y=π−sin−1z
Or x√1−y2+y√1−x2=z
Or x2(1−y2)=22+y2(1−x2)−2yz√1−x2
Or (x2−z2−y2)2=4y2z2(1−x2)
Or x4+y4+z4−2x2z2+2y2z2−2x2y2+4x2y2z2−4y2z2=0
Or x4+y4+z4+4x2y2z2=2x2y2+y2z2+z2x2
∴k=2