Instead of having a dedicated Key to produce symbols such as triangles.

Use your Character Map.

This is accessed by the following:

Start > All Programs > Accessories > System Tools > Character Map
At the top of the Window, select a font. Try Wingdings 3 if you have it. Now scroll down till you see the triangles. They come in solid form or out line. Highlight your choice > Click the 'Select' tab > Copy.

Now open the program you want to use them with and paste them in.

However, some programs that have the ability to produce Text can give access direct from them rather than using the Character Map. Where do you want to use the 'Triangles' symbols?