2015年全国初中数学联赛四川赛区决赛第12题如图1,在等腰三角形ABC中,O为线段AB的中点,线段OC与以AB为直径的☉O交于点D,射线BD交AC于点E,若AE=CD,求证:∠BAC=90°.图1这是一道圆与直线型的综合题,是几何题的压轴题,具有一定的难度,我们深入探究此 As shown in Figure 1, in the isosceles triangle ABC, O is the midpoint of the line segment AB, and the line segment OC and the line AB with the diameter AB intersect at the point D, and the line BD AC At point E, if AE = CD, verify: ∠ BAC = 90 °. Figure 1 This is a round and linear synthesis of questions, is the subject of the pressure of the subject of the problem, with a certain degree of difficulty, we explore this in-depth