00:01
In this exercise, we have these three vectors, a, b, and c that are shown here in the screen, and we have to calculate the dot product between them.
00:11
In question a, we have to calculate a .b.
00:18
Now remember that the dot product can be calculated as the magnitude of vector a times the magnitude of vector b times the cosine of the angle theta between the two vectors.
00:31
Now notice that the angle between the two vectors, this angle theta here is such that theta is equal to 180 degrees minus 30 degrees.
00:46
So it's 150 degrees.
00:50
So a .b is equal to the magnitude of a, which is 8 meters, times the magnitude of b, which is 15 meters, times the cosine of 150 degrees.
01:03
And this is equal to minus 104 meters squared.
01:16
This is zeta b.
01:21
Then in question b, we have to calculate b .c and b.
01:29
And b .c is equal to the magnitude of b times the magnitude of c times the cosine of the angle theta between them...