Here is my version of the triangle. It took me a while to figure out how to get this to work. Finally I figured it out using a png so my white background didn't show. Hope this is what you were looking for.
oh dang it janet... you said inside! grrrr I need to learn to read in the heat wave we are encountering... will MOSTLY in do? If not let me know please Miss A... will crop over hanging bits off it for the challenge if required... for me though I am leaving it just as it is! altered to meet challenge requirements...