Area, SM-Bank 036

A windscreen wiper blade can clean a large area of windscreen glass, as shown by the shaded area in the diagram below.
 

The windscreen wiper blade is cm long and it is attached to a cm long arm.

The arm and blade move back and forth in a circular arc with an angle of at the centre.

Calculate the area cleaned by this blade, in square centimetres, correct to one decimal place.  (2 marks)

NOTE: