consider X-axis along the east-west direction and north-south direction along Y-axis
A = magnitude of distance traveled by hiker in north-east direction = 30 kilometer
θ = angle of direction of displacement of the hiker relative to x-axis or east direction = 45 degree counterclockwise
A' = component of distance traveled by the hiker along the east direction.
Since the angle is given with the x-axis, the Sin provides the component in Y-direction. hence
Using the equation
A' = A Sinθ
Inserting the values
A' = (30) Sin45
A' = 21.2 km