Help please, I only know how to do pyramids with square bases. I don't know with triangular, hexagonal etc.

An edge of the base of a regular triangular pyramid is 12cm. Find the slant height and the total area if the altitude of the pyramid is 20cm.

Could you also show it when it is a hexagonal base?

Also please show me how to draw the figure and where are the corresponding parts (slant height, height, edge etc.)

Thank you!