Adding vectors by components
Hello, I don't have a question about how to solve this problem, but I can not for the life of me figure out how the author comes up with θ. Here is the problem:
In a road rally, you are given the following instructions: from the starting point use available roads to drive 36 km due east to checkpoint, then 42 km due north, and then 25 km northwest.
Q) What are the magnitude and orientation of your displacement "d" from the starting point?
They also provide a figure that includeds the angle (below), but I can't figure out how it's derived.
