If sin−1xa=cos−1xb=tan−1yc;0

sin−1xa=cos−1xb=tan−1yc=sin−1x+cos-1xa+b=π2a+b , it gives tan−1y=πc2a+buse trianglecosπca+b=cos2tan−1y=1−y21+y2                                       {   formula   sin-1x +cos-1x =π2    }