Question

An observer for a radar station is located at the origin of a coordinate system. Find the bearing of an airplane located at that point.
(-4,0)

Answer 1

the answer in the back of the book says 270 degree; N 90 degree W, or
S 90 degree W. I don't get how they get that answer.

Answer 2

If you start facing north and can only turn clockwise, how many degrees are you turning?
Or, if you start facing north, how many degrees will you turn counter-clockwise?

Answer 3

Can you clarify that a little better? I still don't really get it.

Answer 4

Going from west to north or south would be 90 degree, so does that mean that any point with 0 in the x or y axis would also be 90 degree?

Answer 5

@artemisxrpg
Refer to @gypsy1274's diagram.

Modern aviation bearing convention:
If you are standing at the origin and facing North, straight up, and then rotate clockwise 90 degrees, then 90 more and then 90 more, you then be facing 270 degrees.

Iron men and wooden ships convention
While facing North if one turns counter clockwise 90 degrees then one ends up facing 270 degrees, however, one has rotated 90 degrees toward the west from the initial North facing direction and therefore one's current heading is North 90 degrees West.

The same idea holds when facing due South. If one then rotates clockwise 90 degrees, one ends up facing 270 degrees, or South (by rotating) 90 degrees West.

Rectangular coordinate system, Mathematics
If you are facing straight up, 90 degrees, and then rotate clockwise 270 degrees you will end up facing "due west" which is 180 degrees in math land.