### how to insert delta and nebula inside the basic shapes in libre impress office

Hello,
In libre impress office normally if i go to insert->objects -> formula, i can type %DELTA (to get delta) and nebula(to get nebula) to get the functions/mathematical/greek functions. But now i have to make it a schematic representation, so, i have added a rectangle from basic shapes. And now inside this rectangle that i have taken from basic shapes, i want to type the formulas along with the text, but here the object option and it doesn't show any formula option at all.
So, my question is how to type the formulas along with the text (since i have a sentence with contains text with formulas) in libre impress office.

Thank you..