00:01
Hi there, so for this problem, we need to solve the following operations by the figures that we are, by the vectors that we are provided in here.
00:12
So for example, the first expression that we need to calculate, it will be a dot product with f plus two times c.
00:26
So first of all, let's write these three vectors in a vector form.
00:29
So for example for the vector a, as you can see from the figure, the vector a is in the first quadrant.
00:37
So both the x component and the y component are positive and the angle is with respect to the horizontal.
00:46
So when we calculate the x component, that will be given by the cosine of that angle.
00:51
So that will be the magnitude that we are given for this, that is 10, this times the cosine of 30 degrees.
00:57
This in the x -derption plus 10 times the sign of 30 degrees, that in the wide direction.
01:04
Now, once we have this, also we need to write the vector f.
01:10
As you can see from the figure, the vector f is downward and to the left, so that means that it is in the third quadrant, so both components are negative.
01:21
So the magnitude and the angle is given with respect to the horizontal.
01:24
So then the x component is as well given by the cosine of that angle.
01:31
So that will be minus its magnitude times the cosine of 30 degrees.
01:38
Then this in the x eruption plus 20 times the sign of 30 degrees.
01:44
This is in the wide eruption.
01:45
Now for the better, as you can see from the figure, it's in the fourth quadrant.
01:49
So the white component is negative and the x company is positive.
01:54
Again, the angle is given good respect to the horizontal, so then this will be the edge component positive.
02:01
The magnitude is 12, 12 times the cosine of 60 degrees.
02:05
Then this minus 12 times the sign of 60 degrees, this in the y direction.
02:12
Okay, so once we have this, what we need to do is to do this operation in here.
02:17
I'm going to lift that to you, but you just need to see multiplied, each term by two.
02:27
So then for example, two times this, what are you need to change our this value? so that will give us 24, 24, because that is 2 times 12.
02:36
And then apt them these two together.
02:40
And then that result, you do the dot product with a.
02:44
Remember that when we do the product, for example, product of a time a dot product with some vector, let's say f, that will be the x component of a times the x component of b plus the y component of a times the y component of b.
03:03
So first you need to do f plus 2 times c and then that dot product with a.
03:09
Now let's pass now to part e of this problem, which is the dot product between i and this dot product with b.
03:17
First let's write what it is b.
03:19
B, as you can see from the figure, it is in the first quadrant...