What does the formula of the auxiliary line of mathematical geometry in junior high school mean: "Find tangent chords, diagonal lines with the same arc, etc."
On both sides of the tangent angle, one is tangent and the other is chord; The same arc is an arc sandwiched by the chord tangent angle, and the diagonal is the circumferential angle of this arc, which means that the circumferential angle of this arc is equal to this chord tangent angle. I searched it and found it all. Popular enough! Hmm. How interesting ....
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