Dynamic Block - Rotate in opposite directions at once

[dpagd]

This has stumped me, so turning to wider community for assitance. 

I'm trying to compile dynamic lighting symbols and one of the elements that is sometimes useful to show is the beam angle.

I'd like to be able to rotate the beam angle out on one side and have the opposing line move equally in the other direction.

I found the below within reply 5 and have actioned it to limited success

http://forums.augi.com/showthread.php?104992-Opposite-Rotation

I'm working in auotcad LT 2014 so it looks like I can't generate parametric and geometrical constraints which would the obvious way.

Consequently I'm working with the first method in the above link. The problem is that this has a limited range before the scale turns back on itself and the relationship breaks down. Ideally i'd like to be able to go up to 180° (90° on each line). 

This 'module' of the dynamic block will then be put through scaling and rotation to allow me to 'aim' the luminaire and have the beam angle reach the subject.

As a secondary question - Is there a way to allow me to enter decimal angles into the paramaters as at present if I enter 0.5 it rounds to 1 which would mean the system can only work in 2° increments (each line moving 1° away from eachother). I'm hoping this is a simple setting. 

I attach a very simple set of lines that I'm exploring to keep this part simple. I've dilliberately left the Polar handles on as it allows me to see where the issue occurs. 

Any thoughts or guidance would be appreciated, my apologies if I'm being thick in this matter.

Thanks in advance

[dpagd]

I should add that If i have to use look-up tables then I can do, I was just having difficultly taking one rotate parameter to impact another. Again probably just my inexperience.