We know that in writings in mathematics, variables are usually italicised. Now the question is, in handwriting on the board, how should we write the variables differently?
As an example, say I want to write the following:
The following statement is true for all real number $x$: $$\sin^2 x+\cos^2 x=1.$$
Here are some possibilities:
- Write the variable $x$ as x without any changes in the font.
- Purposefully write $x$ using a "handwritten italic" font.
- Write $x$ as x but with a different colour.
Is there any preferred/suggested practice on this?