Symbolic Small Quantity Approximation in MATLAB

Question

I am trying to make a small angle approximation in MATLAB's symbolic toolbox. This is being used for the equations of motion in a spacecraft control simulation (and yes, I need to linearize, I can't leave them in their more exact form). For those unfamiliar, the small quantity approximation does a few main things that I need. For small quantities delta and gamma,

1. delta times gamma is approximately 0
2. delta^2 is approximately 0 (same with higher powers)
3. sin(delta) is approximately delta
4. cos(delta) is approximately 1

I have tried using MATLAB's taylor function (link here), but it doesn't seem to be doing what I want except in a very specific scenario (which I am sure is coincidental anyway). A test case is presented below:

syms psiX psiY psiZ rGMag mu Ixx Iyy Izz
QLB = [1,psiZ,-psiY;-psiZ,1,psiX;psiY,-psiX,1]; %linearized version of the rotation matrix from the L frame to the B frame
rG_LVLH = [0;0;rGMag]; %magnitude of the rG vector expressed in the L frame
rG = QLB*rG_LVLH
G = 3*mu/rGMag^5 .* [rG(2)*rG(3)*(Izz-Iyy);rG(1)*rG(3)*(Ixx-Izz);rG(1)*rG(2)*(Iyy-Ixx)]; %gravity-gradient torque

The desired output of the above should have the G vector with a 0 in the third component and symbolic variables left in the other two. This particular example doesn't include a trigonometric example, but I can provide if necessary. Thanks.