In the following diagram, a circle has radius r (metres), and angle $latex \theta$ (radians), and centre O.

The area of the shaded sector is $latex \frac{6\pi }{5}$, and the length of the sector AB is $latex \frac{3\pi }{5}$.

a) Find the value of r.

[Maximum mark: 3]b) Find the value of $latex \theta $.

[Maximum mark: 3]