# Numbering in Align

I am looking to remove the numbering from some equations using align and text (see MWE). I have read many posts on this page and tried adding \nonumber and \notag at the end of my second equation and have received error messages.

"Package amsmath Error: Multiple \label's: label 'Equ:ConeAng' will be lost. \end{align}" with \notag

\documentclass[english,10pt,letterpaper]{article}

\usepackage{array}
\usepackage{babel}
\usepackage{mathtools}

\begin{document}

\begin{align}
\shortintertext{Radial difference outside diameter and inside diameter of the cone. (in)}
C &= \cfrac{B-A}{2} \label{Equ:C} = \;B'-A'
\intertext{Cone angle. (degrees)}
E &= tan^{-1}\left(\cfrac{C}{D}\right) \label{Equ:ConeAng}
\intertext{Diagonal length of flat cone. (in)}
F &= \cfrac{C}{sin(E)} \label{Equ:DiagL}
\end{align}

\end{document}

• Indent code with the [ {} ] button... Oct 14 '16 at 19:34
• would it be simpler to set them as a series of equation environments? There's no real need for align here... Oct 14 '16 at 19:36
• i think that the \shortintertext{...} needn't be within the scope of align, and it really isn't "short"; but the other two \intertext{...} entries are short. also, i believe that there should be \\  at the ends of the lines before the \intertext bits, and that there is a warning in your log file saying that these have been added (silently). (unfortunately, i'm not somewhere that i can check this easily.) Oct 15 '16 at 0:40

The \label does not work in the unnumbered equation. The equation environments of amsmath need to do some special treatment for the \label support, which restricts the \label commands to one per numbered equation. Without \label, the commands \nonumber or \notag are working:

\documentclass[english,10pt,letterpaper]{article}

\usepackage{array}
\usepackage{babel}
\usepackage{mathtools}

\begin{document}

\begin{align}
\shortintertext{Radial difference outside diameter and inside diameter of the co
C &= \cfrac{B-A}{2} \label{Equ:C} = \;B'-A'
\intertext{Cone angle. (degrees)}
E &= \tan^{-1}\left(\cfrac{C}{D}\right) \nonumber
\intertext{Diagonal length of flat cone. (in)}
F &= \cfrac{C}{\sin(E)} \label{Equ:DiagL}
\end{align}

\end{document}