Uhhh, I understand the idea you were going for, but I really disagree. Usually, a triangel is formed by the outer edges being defined, rather than lines running out to the corners. It is a good idea, but I don't feel it fits within the definition of the challenge. Additionally, I think that the shot could have been lit a lot better, and you could have chosen a tulip with a lot better colors. Nice shot anyway I suppose.
great idea and subject. The focus is a little soft though: ways to change that include
1) use of USM before submitting
2) use of higher aperature while shooting
--> if possible, get the shot on a sunny day, it'll give you more light, a smaller aperature, and more interesting contrasts of the topography of the flower
3) did you use a tripod?