Finding magnitude A from a vector component equation

[MarXphysics]

1.I only need to know how to get magnitude out of a vector



2. Suchs as 25m = a cos (60 degrees)


3. I tried 25m/cos/60degrees but it don't seem right

please assist I know it isn't a real problem it's just the step that I need help. If you could write it in fomula form AX=A cos (theta) solving for "A". And if you can show me how to solve for "theta" as well please.

 

[granpa]

magnitude is simply the length of the vector. if you are using cos then it sounds like what you really need is the x or y component.

 

[MarXphysics]

I see that I may have been unclear Ax is the x component. I have Ax and I have ethe angle theta what I do no thave is the magnitude.

 

[granpa]

A_x is written A(sub)x(/sub) except that you use brackets.

 

[granpa]

what do you mean solve for A? that's trivial. A*cos(theta) is no different from A*B.

theta is a little harder. give me a minute.

 

[MarXphysics]

Thanks_you
I have A_x = A cos $$\Theta$$
where I know A_x and $$\Theta$$
how do I find A

 

[granpa]

solving for theta:

http://en.wikipedia.org/wiki/Trigonometric_function#Inverse_functions