A solid disc of radius ' a ' and mass ' m ' rolls down without slipping on an inclined plane making an angle θ with the horizontal. The acceleration…

A solid disc of radius ' a ' and mass ' m ' rolls down without slipping on an inclined plane making an angle $\displaystyle \theta$ with the horizontal. The acceleration of the disc will be $\displaystyle \frac{2}{\mathrm{~b}} \mathrm{~g} \sin \theta$ where b is \_\_\_\_. (Round off to the Nearest Integer) ( $\displaystyle \mathrm{g}=$ acceleration due to gravity $\displaystyle \theta=$ angle as shown in figure)