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知识要点一圆的有关性质1.圆周角与圆心角:一条弧所对的圆周角等于它所对的圆心角的一半.验证这一性质时,运用了分类讨论思想.2.圆周角与半圆或直径:半圆或直径所对的圆周角是直角;90°的圆周角所对的弦是圆的直径.
Knowledge about the nature of a round 1. Circumference angle and the central angle: an arc of the circumference of the angle equal to half of the center angle it is to verify the nature of the classification discussed the idea of using the circle angle and the semicircle Or Diameter: The angle of the circle to which the semicircle or diameter corresponds is a right angle; the chord to which the angle of 90 ° is directed is the diameter of the circle.