new symbols of <> with larger angle between two arms

Question

In below figure we pointed to <i,j>

But we wish to have a special symbol instead of <>. In the new symbol we expect that the angle between the two arms are larger than default <> i.e., the below symbols

Answer 1

I think you're looking for \langle and \rangle.

\documentclass{article}
\begin{document}
\( < i, j > \)

\( \langle i,j \rangle \)
\end{document}

Answer 2

Do you want increasing the size of \langle or \rangle? If the answer is "yes" you can choose the scalerel package to pag. 7 (for example):

\documentclass[a4paper,12pt]{article}
\usepackage{amsmath,amssymb}
\usepackage{scalerel}
\begin{document}
$\stretchto[200]{\langle}{20pt}x,y\stretchto[200]{\rangle}{20pt}$
\end{document}

If you want double \langle (\rangle) you can use \llangle or \rrangle with MnSymbol package.

Answer 3

Perhaps \left\langle ... \right\rangle? That should adjust the size to the contents.