Problem 14.

Mr. Letourneau is flying his broom stick parallel to the ground. He undergoes two consecutive displacements. The first is 100 km 10 degrees west of north, and the second is 120 km 50 degrees east of north. What is the magnitude of the broom stick's displacement? 

Solution:

The displacement are shown schematically in the figure. From this figure we can see that the angle between the first and the second displacements is . Then from the triangle based on the first, second, and net displacements we can find the magnitude of the net displacement (cosine formula):