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## Homework Statement

## Homework Equations

## The Attempt at a Solution

Well, I have the whole thing drawn out, and calculated some information that will be needed.

[itex]|A|=7.92[/itex]

[itex]|B|=8.28[/itex]

I am assuming that the question means that vector

**C**is perpendicular with vector

**A**, meaning, there is 90 degrees between them.

a.) Find the x component of

**C**

It says that the scalar product of

**C**and

**B**is 13, so I am guessing that means I have to know the angle between those two vectors. Which would be the angle between

**B**and

**A**minus 90 degrees right?

How do I find the angle between

**B**and

**A**?

Alright, so:

[tex]A\bullet B = (4.8)(-3.9)+(-6.3)(7.3)[/tex]

[tex]A\bullet B = -64.71[/tex]

and since [itex]A\bullet B = |A||B|cos(\theta)[/itex]

[tex]|A||B|cos(\theta) = -64.71[/tex]

[tex]cos(\theta) = \frac{-64.71}{(7.92)(8.28)}[/tex]

[tex]\theta = 170.67 degrees[/tex]

Then the angle between B and C is 80.67 degrees, which looks about right.

So then, the scalar/dot product of C and B is:

[tex]C \bullet B = |8.28||C|cos(80.67) = 13[/tex]

[tex]|C| = \frac{13}{cos(80.67)|8.28|}[/tex]

[tex]|C| = 9.68[/tex]

Now what?

I don't see how the components of C are coming out of this.

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