How to apply Givens rotation to a matrix with complex elements?

Question

I am trying to apply Givens rotation to a matrix, I could do it when the matrix had real values. For example, for this matrix:
$A=\begin{bmatrix}3&5\\4&1\end{bmatrix}$
I can simply calculate $sin$ and $cos$ like this:
$r=\sqrt{3^2+4^2}=5$
$cos=3/r=0.6, sin=4/r=0.8$
But when the values are complex numbers, I have a problem in determining which value of $r$ to select. For example: $A=\begin{bmatrix}3+1.5i&5-7i\\4-2i&1+3i\end{bmatrix}$
$r=((3+1.5i)^2+(4-2i)^2)^{0.5}=4.403-0.795i$ or $-4.403+0.795i$
So the question is, Which value of $r$ should I select? What is the criteria?