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symbols - How to insert a triangle/rectangle with plus sign in it (abstract algebra operators)? - TeX - LaTeX Stack Exchange
![symbols - How to insert a triangle/rectangle with plus sign in it (abstract algebra operators)? - TeX - LaTeX Stack Exchange symbols - How to insert a triangle/rectangle with plus sign in it (abstract algebra operators)? - TeX - LaTeX Stack Exchange](https://i.stack.imgur.com/QGWKa.png)
symbols - How to insert a triangle/rectangle with plus sign in it (abstract algebra operators)? - TeX - LaTeX Stack Exchange
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