In the figure O is the centre of a circle of radius $5\;cm$ . T is a point such that $OT= 13\;cm$ and OT intersects the circle at E. If AB is the tangent to the circle at E , then the length of AB is ______

Question

$\begin{array}{1 1} 20\;cm\\ 10\;cm \\\frac{20}{3}\;cm \\ \frac{10}{3} \;cm \end{array}$