Which formula can be used to find the x-component of the resultant vector? tx - ux - vx tx + ux + vx tx = tcosθ tx = tsinθ

If you are simply looking for the X component then the most applicable formula from the choices given is Tx + Ux+ Vx. This means that you will add all x-components. 

For example:

If a man walking along the x-axis walks 10 meters to the right, 5 back and 2 meters forward, what is the resultant vector?

Using the formula
10 meters + (-5 meters) + 2 meters = 7 meters

Even when solving the y- component of the resultant vector, you will add them together but using only measures following the y-axis.