if a and b are unit vectors and the angle between them is 60degrees calculate |3a-5b|

There are unit symbols on a and b. Can someone help me walk through this question?

Question

if a and b are unit vectors and the angle between them is 60degrees calculate |3a-5b|

There are unit symbols on a and b. Can someone help me walk through this question?

anonymous · Answer

Are you familiar with the dot product equation
$$a\cdot b=|a||b|\cos \theta?$$
Here, a and b are two given vectors, 
|a| and |b| are the magnitudes/norms of vectors a and b, and
theta is the angle between the vectors a and b.