For each of the given vectors, give a vector that, when added to it, yields a null vector (a vector with a magnitude of zero). Express the vector in the form other than that in which it is given (component or magnitude- angle):

(a) \(\overrightarrow{\boldsymbol{A}}=4.5 \mathrm{~cm}, 40^{\circ}\) above the \(+x\)-axis;

(b) \(\overrightarrow{\mathbf{B}}=(2.0 \mathrm{~cm}) \hat{\mathbf{x}}-(4.0 \mathrm{~cm}) \hat{\mathbf{y}}\);

(c) \(\overrightarrow{\mathbf{C}}=8.0 \mathrm{~cm}\) at an angle of \(60^{\circ}\) above the \(-x\)-axis.