Question

in anniversary celebration of Marilyn bell's 1954 feat - she was the first person to swim across lake Ontario - a swimmer set out from the shores of New York and maintained a velocity of 4 m/s [N]. as the swimmer approached the Ontario's shore, she encountered a cross-current of 2 m/s [E 25˚S]. calculate her velocity with the respect to the crowd from the beach (with respect to the ground).

Answer 1

add the two velocities:
v = <0,4> + <4cos25°,-4sin25°> = <x,y>

Answer 2

All angles are measured CW from +y-axis.
Vr = 4m/s[0o] + 2m/s[115o],
Vr = (4*sin0+2*sin115) + (4*cos0+2*cos115)i,
Vr = 1.81 + 3.15i = 3.63m/s[29.9o] CW. = resultant velocity.