I am trying to store three variables $$A=2.42528, B=1.41421, c= 1.61106$$ that I can change at anytime and then calculate the following equation:
$$\theta_4=2\left[{tan^{-1}\left(\frac{-B\pm\sqrt{B^2-4AC}}{2A}\right)}\right]$$
I have used $ctrl + var$ to store $a$, $b$ and $c$ (note I couldn't store them in capitals like I needed). I then went to $menu→$ $Actions→$ $Define$ and typed:
$$Define \space\theta4=2\left[{tan^{-1}\left(\frac{-b\pm\sqrt{b^2-4ac}}{2a}\right)}\right]$$
and hit enter and was shown $Done$ on the screen. However when I typed in $\theta4$ and hit enter, it seems as though it only calculated the equation using the variable $b$. It gave me the output:
$$0.620709\cdot tan^{-1}\left(\sqrt{-4\cdot (ac-0.5)}+1.41421\right)$$
It is worth noting when I actually substitute both $a$ and $c$ into the equation at this point I am shown $Error: \space Domain\space error$
So my question is, how to I get my equation to include all of the variables defined within it, and then why I am I getting a domain error? Thank you