# How can I position the tag of a “nested” aligned environment?

I have an equation that is two wide to fit on a single line, but it has \left(-\right) split over two lines, and I can't align to something inside these for some reason... The wanted output is something like this:

A = B ( C
+ D ) (1)


The best I can do is this:

\documentclass{article}
\usepackage{amsmath}
\begin{document}
A = \begin{aligned}[t] &\left( B \right. \\ &\phantom{(} \left. + C \right) \end{aligned} %\raisetag{-1\baselineskip} <- doesn't work :-(
\end{document}


But this places the equation number on the top line, which looks very awkward when the horizontal spacing is a lot more compact than in this isolated example.

What magic ritual do I need to perform for the proper layout of this equation?

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It should be \raisetag{-1\baselineskip}. –  Henri Menke Jul 17 '14 at 13:03
@Henri true, typo, but that doesn't work. –  rubenvb Jul 17 '14 at 13:05
–  Henri Menke Jul 17 '14 at 13:10

I'd do something like this

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
A &= \Bigl( B  \notag \\
&\phantom{= \Bigl(}  + C \Bigr)
\end{align}
\end{document}


or using split

\documentclass{article}
\usepackage{amsmath}
\begin{document}
$$\begin{split} A &= \Bigl( B \\ &\phantom{= \Bigl(} + C \Bigr) \end{split}$$
\end{document}


The latest will write the number of the equation in the middle of the multiple-line equation.

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Please always use \Bigl and \Bigr to get the correct spacing for opening and closing delimiters. –  Henri Menke Jul 17 '14 at 13:11
@HenriMenke Wow... I didn't knew that! Thank you for the advise, I'll change the examples! –  Dox Jul 17 '14 at 13:13

As \raisetag doesn't seem to work properly here the align environment looks like a decent solution:

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{align}
A = &\left( B \right. \notag \\
&\phantom{(} \left. + C \right)
\end{align}
\end{document}


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