Question

Meaning of pair of tangents to a hyperbola

Answer 1

x2a2−y2b2=1x2a2−y2b2=1

from an external point (x1,y1)(x1,y1).

My book says that the answer is SS1=T2SS1=T2, where

S=x2a2−y2b2−1S1=x21a2−y21b2−1T=xx1a2−yy1b2−1S=x2a2−y2b2−1S1=x12a2−y12b2−1T=xx1a2−yy1b2−1

But I can't get this result. Please help me go about this problem.