How to draw an euqilateral triangle.

Hey, I've been at this for a few days now and I cannot for the life of me figure this one out.

I need to draw a trinagle with "*" and "-" that looks like this

*--------

**-------

***------

****-----

*****----

****-----

***------

**-------

*--------

it doesn't look like it in the picture but the picture is supposed to be a complete square with and odd number of rows and columns.

I am at my wit's end on this. I don't even know how to begin on this. In the rest of my program I have already used FOR loops to draw other types of triangles, but this one is just killing me. Thank you for any help. It is greatly appreciated.