I down loaded the latest os for my iphone and found that if you go to the compass swipe to the next page there are these two circles. If you hold the iPhone perfectly flat one is over the other and shows 0 degrees. As you tip the iphone the circles separate and give you the degrees your iphone is tipping. Now you can use your iphone to achieve the perfect 30 degree hang angle.
And now you know the rest of the story.
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