What is the Equation for Finding Vector Magnitude in 2D and 3D?

[needsphysics]

Homework Statement

Vx = 18 m/s and Vy = 45 m/s

Homework Equations

This is what I am not understanding, could anyone help with the equation process to finding the magnitude?

Thank you!

 

[cwasdqwe]

Do we know if the movement takes place in 2 or in 3 dimensions?

 

[nrqed]

Do we know if the movement takes place in 2 or in 3 dimensions?

It does not matter.

To the OP: what is the formula for the magnitude of a vector if we know all its components? You must have seen this somewhere...

 

[cwasdqwe]

...what is the formula for the magnitude of a vector if we know all its components? You must have seen this somewhere...

To define all its components you must know the dimension... but okay, let's assume $v_{z}=0$...

 

[nrqed]

To define all its components you must know the dimension... but okay, let's assume $v_{z}=0$...

Yes, I assume that $v_z =0$ since no value is provided. It would be strange if $v_z$ was not zero and they would not give us the value. My point is that then we get the same answer whether we use the magnitude equation in 2D or in 3D.