Improve the parenthesis in the circuit gates documentation

What is the expected enhancement?

In many place our documentation shows LaTeX fractions that are larger than the surrounding parenthesis. For example in the sine and cosines in the UGate documentation we have

That’s because we don’t use the \left \right or \big commands if a parenthesis surrounds a \frac-fraction. It would be nice if we could go through the docs and ensure everything is nicely rendered by e.g. replacing occurances as

        \newcommand{\th}{\frac{\theta}{2}}
        U(\theta, \phi, \lambda) =
            \begin{pmatrix}
                \cos(\th)          & -e^{i\lambda}\sin(\th) \\
                e^{i\phi}\sin(\th) & e^{i(\phi+\lambda)}\cos(\th)
            \end{pmatrix}

with

        \newcommand{\th}{\frac{\theta}{2}}
        U(\theta, \phi, \lambda) =
            \begin{pmatrix}
                \cos\left(\th\right)          & -e^{i\lambda}\sin\left(\th\right) \\
                e^{i\phi}\sin\left(\th\right) & e^{i(\phi+\lambda)}\cos\left(\th\right)
            \end{pmatrix}

[jakelishman]

Thanks for your interest, @stoicodin, but this issue has already been solved by @saktar-unr in #7872. You can see the context and linked pull requests above. If you’d like to find something else to work on, please have a look at the issues tagged “good first issue”.

[Cryoris]

Just one pull request for all of them would be good! You can build the documentation locally and check there how it looks like. If you have tox installed you should be able to do that by calling tox -edocs in the qiskit-terra root folder 🙂