2. A car moves round a bend which is banked at a constant angle of \(10 ^ { \circ }\) to the horizontal. When the car is travelling at a constant speed of \(18 \mathrm {~m} \mathrm {~s} ^ { - 1 }\), there is no sideways frictional force on the car. The car is modelled as a particle moving in a horizontal circle of radius \(r\) metres. Calculate the value of \(r\).
(6)