In certain navigation or surveying problems, the direction, or bearing, from a point P to a point Q is specified
by stating the acute angle that segment PQ makes with the north-south line through P. We also state whether Q is
north or south and east or west of P. Figure 6 illustrates four possibilities. The bearing from P to Q1 is 25° east of
north and is denoted by N25°E. We also refer to the direction N25°E, meaning the direction from P to Q1. The
bearings from P to Q2, to Q3, and to Q4 are represented in a similar manner in the figure. Note that when this
notation is used for bearings or directions, N or S always appears to the left of the angle and W or E to the right.
In air navigation, directions and bearings are specified by measuring from the north in a clockwise direction. In
this case, a positive measure is assigned to the angle instead of the negative measure to which we are accustomed
for clockwise rotations. Referring to Figure 7, we see that the direction of PQ is 40° and the direction of PR is
300°.