When you create a diagram in Math Illustrations you get all the symbols without any effort! When you constrain or annotate a line, the length symbols is added automatically. This is true for any annotation or constraint that you add!

The following is a demonstration of how easy it is to create a triangle and label its sides. As an added bonus the video also shows how easy it is to paste your figure into Word!

https://mathillustrations.com/draw.php