The length of a tangent from a point A at distance 10 cm from the centre of the circle is 8 cm. Find the radius of the circle.

(c): Given, OP = 10 cm and AM = 8 cm (let M be point of contact for Tangney) $\because$ $OM\perp LAM$ ($\because$ Radius is perpendicular to AM) In right $\Delta OMA,O$A$2$=O$M$2$+M$A$2$ $\Rightarrow$ $10$2$=O$M$2$+$8$2⇒O$M$2$=100-64=36$ $\Rightarrow$ $OM=6cm$ Hence, radius of the circle is 6 cm.