# Dot product

1. Apr 5, 2008

### chocolatelover

1. The problem statement, all variables and given/known data
Vector A has a magnitude of 5.00 units, and vector B has a magnitude of 9.00 units. The two vectors make an angle of 49° with each other. Find (vector A)(vector B)

2. Relevant equations

3. The attempt at a solution

(5i+0j)(0i+9j)=
(5N)(0m)+(0N)(9m)=

square root (5^2+0^2)
=5N

Could someone please tell me if this is correct and if not could someone show me how to do it?

Thank you very much

2. Apr 5, 2008

### Shooting Star

(vector A)(vector B)?

This notation does not mean anything. Possibly, you mean the scalar product A.B?

How did you utilize the 49 deg given in the problem?

A.B = (magnitude A)(magnitude B)cos $\theta$, where $\theta$ is the angle between A and B.

Take my advice given in the other post.

3. Apr 6, 2008

Thank you

Regards