We got this to shade a sandbox in a 90 degree angle corner of our yard.  I wouldn't say this is a true triangle.  The points/corners are skinnier than you can tell in the photo. It works well for most of the day, but due to the slightly odd shape it is not directly over the sandbox but further out in the yard than I anticipated.  You do need your own hardware to attach it.  We purchased eye hooks from  a big box store, screwed them into the fence, and then tied the strings to them.