Question

Please send the explanation also​

Answer 1

Answer:

length of OA is 13 cm

Step-by-step explanation:

radius at the point of contact is 90 degree

therefore OAB is a right triangle

so by applying Pythagoras theorem we get OA as 13

Answer 2

Answer:

Question :

AB is a tangent. Find the length of radius.

Answer :

$If \: AB \: is \: a \: tangent \: it \: is \: perpendicular \: to \: \\ OA \: the \: triangle \: is \: a \: right \: angled \: triangle. \\ \\ By \: Pythagoras \: theorem \: \\ {OA}^{2} + {AB}^{2} = {OB}^{2} \\ \\ {OA}^{2} + {12}^{2} = {15}^{2} \\ \\ {OA}^{2} + 144 = 225 \\ \\ {OA}^{2} = 225 - 144 = 81 \\ \\ {OA}^{2} = 81 \\ \\ OA \: = \sqrt{81} = \sqrt{9 \times 9} \\ \\ OA = 9cm. \\ \\ \\ Therefore \: the \: radius \: of \: the \: triangle \\ \: OA \: = \: 9cm.$