Just throwing this out there (I am still new to this board) but when a semicircle bounded by the diameter has a triangle embedded in it. Does the middle angle have to be 90 degrees?? and if it is bounded by a chord are there are no rules for the angle?
Does the rest point ( besides the two points as the two ends of the diameter) lie on the semicircle?! ..If it does, the middle angle is 90.
In case of a chord, the middle angle can't be 90. If you are interested in knowing why, you can refer to my illustration
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