There are countless ways to create a triangle stretch, so there is no specific route combination. The idea is to combine a horizontal stretch with a vertical stretch, and provide the QB with a triangle read in a specific area of the field. Running it from a bunched formation gives it a man coverage busting element to the route combination.
The Corner (yellow) and the Curl (orange) create a vertical stretch. The Curl and the Out (red) create a horizontal stretch.
Progression for this specific route combination: Corner - Out - Curl
![](http://i1280.photobucket.com/albums/a499/thl408/thl408001/all22/pre_zpsn7lk1edw.png)
Blue is vertically stretched as he is wary of the Corner route and has his hips turned upfield. Orange is horizontally stretched as he is wary of the Curl. This opens a window for the Out route to be targeted.
![](http://i1280.photobucket.com/albums/a499/thl408/thl408001/all22/post_zpsx5rrluqn.png)
vs Cover3
![](http://i1280.photobucket.com/albums/a499/thl408/thl408001/all22/chispottriangle_zpse5nrytmk.gif)
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The Snag (yellow) and the Curl (red) create the vertical stretch. The Curl and the Flat (orange) create the horizontal stretch.
Progression: Flat - Curl - Snag
![](http://i1280.photobucket.com/albums/a499/thl408/thl408001/all22/prereal_zpscmhjo4a8.png)
Blue is vertically stretched. Orange is horizontally stretched.
![](http://i1280.photobucket.com/albums/a499/thl408/thl408001/all22/post1_zps0rxkwrjq.png)
vs Tampa2
![](http://i1280.photobucket.com/albums/a499/thl408/thl408001/all22/5-11-2015_9-46-22_PM_zpschq26s1k.gif)