Current location - Training Enrollment Network - Mathematics courses - How does Qiqihar 20 10 prove that the angle BOC of the last question in the mathematics multiple-choice question of the senior high school entrance examination is equal to EOC?
How does Qiqihar 20 10 prove that the angle BOC of the last question in the mathematics multiple-choice question of the senior high school entrance examination is equal to EOC?
∵△BCD≌△ECA,∴∠GAC=∠FBC，
∴A, B, C, O four-point * * * circle, we can get ∠ BOC = ∠ BAC = 60 from the circle angle theorem.
Similarly, D, E, C, O four-point * * circle can get ∠ EOC = ∠ EDC = 60 from the fillet theorem.