# Find all three components of vector W

1. Oct 17, 2012

### Toranc3

1. The problem statement, all variables and given/known data

W is 8 units in the y-z plane in a direction defined by theta = 120 degrees with respect to the y axis and have a positive z component.

2. Relevant equations
Wy=Wsin(theta)
R^(2)=Rx^(2)+Ry^(2)+Rz^(2)

3. The attempt at a solution
Wy=Wsin(theta)
Wy=8sin(120) =6.9

8^(2)=Sqrt(0^(2)+(6.9)^(2)+(Rz)^(2))

Rz=4.04 units. is this par right? I am not sure how to approach this one. I only how how to deal with x and y axis but not z. Can sombody point me in the right direction? thanks!

Last edited: Oct 17, 2012
2. Oct 18, 2012

### voko

x, y and z are just labels. What is important is that you have two axes and a vector in their plane, at an angle with respect to one axis.

3. Oct 18, 2012

### Toranc3

Would I use y or z with the cosin(theta)? How do I know to what goes with sin and cosin?

4. Oct 18, 2012

### voko

What is the angle with respect to? What do cosine and sine mean? Draw a unit circle, and label the axes with y and z so that things make sense.

5. Oct 18, 2012

Thanks!