The lengths of tangents from two given points to a given circle are t1&t2. If the two points are conjugate to each other w.r.to the given circle the distance between the points will be
Let P and Q be the conjugate points and O be the center.
Since P, Q are conjugate
⟹PQ2=OP2+OQ2–2r2
⟹PQ2=(t21+r2)+(t22+r2)–2r2
⟹PQ2=t21+t22
⟹PQ=√t21+t22