A tangent segment TP is 24 cm long, and T is 25 cm from the centre O of the circle…

The two tangents drawn from an outside point T to a circle are equal: $TP = TQ$. In the right triangle OPT, $PT^2 = OT^2 - OP^2$. The line OT bisects the angle $PTQ$ and also the angle $POQ$. In the figure OPTQ, $\angle POQ + \angle PTQ = 180^\circ$. A tangent from an outside point has the same length on both sides of OT.