Posted by Nick on .
After flying for 15 min in a wind blowing 42 km/h at an angle of 20° south of east, an airplane pilot is over a town that is 42 km due north of the starting point. What is the speed of the airplane relative to the air?

physics 
MathMate,
There are three vectors involved:
A. the flight vector as yet unknown.
B. The wind at 42 km/h at 20° with respect to the xaxis.
C. the resultant: (0,42) km. from the starting point.
Since the vectorial sum of A and B equals C, you can obtain A by adding C and B, both of which are known. 
physics 
Nick,
i need more help

physics 
MathMate,
You will need to know how to add and subtract vectors. Have you done that at school?
There are different methods, depending on what you have learned. It could be graphical by drawing directed arrows and joining them together in the right order. It could be by resolving the vectors into the x and ycomponents.
We need to know more about what you are working on to provide more detailed help.