A motorboat whose speed in still water is 2.60 m/s must aim upstream at an angle of

Question:

A motorboat whose speed in still water is 2.60 m/s must aim upstream at an angle of 28.5o (with respect to a line perpendicular to the shore) in order to travel directly across the stream.
(a) What is the speed of the current?
(b) What is the resultant speed of the boat with respect to the shore? (See Fig. 3-28)