Which of the following transform as components of a 2d vector?

[briteliner]

Homework Statement

which of the following pairs of quantities transform under rotations of the axes as the components of a two-dimensional vector?
a) (x2, -x1)
b) (x2,x1)
c) ((x1)^2,(x2)^2)

Homework Equations

The Attempt at a Solution

Dont know where to start. i'd appreciate just a little guidance :)

 

[Dick]

I'm not quite sure what you mean by that. If you mean does the transformation L((x1,x2))=(x2,-x1) (for a)) correspond to a rotation by some angle theta, look at the formula in your other post and see if it corresponds to some value of theta.