The American Death Triangle is a climbing anchor with a scary name. Will it kill you? Probably not when used with bolts. Should you use it? Almost certainly not.
Why is it bad?
The 2 biggest reasons not to use the American Death Triangle are:
First, it is not redundant. If the sling fails for any reason (such as a falling rock), the anchor ceases to be and you can die.
Second, it can magnify the forces on each anchor point, instead of sharing the load like a good anchor would.
The top of the triangle looks like the 180 degrees that generate infinite force according to force vector charts. In the chart below you can see just 170 degrees is 576% of the load on each anchor point. So how does this really work?
An equilateral triangle (60 degrees) put ~80% force on each bolt. At 130 degrees there was 150% at each. At 40 degrees it was 70%. No matter how you build it, it is worse than a properly built anchor. Anchors should look like a V and climbers call them Xs, see the episode at the bottom for more of that.
Note: The devices used to measure force are not perfect, but super close enough to see the differences.
Typical rappelling scenarios can involve an American Death Triangle of sorts.
American Death Triangles pull the bolts at an inward angle. We tested some exaggerated angles and got 160% of the "rappel force" on each anchor point which isn't really a concern. Bolts are generally super good enough but if you are rappelling off twigs or sketchy gear, keep this in mind.
3 ways to build a top rope anchor