挑战习题
1/5单选题
难度:

1.如图,在三角形纸片ABC中,∠A=65°,∠B=75°,将纸片的一角折叠(折痕为DE),使点C落在△ABC内的C′处,若∠AEC′=20°,则∠BDC′的度数是(  )
A 30°
B 40°
C 50°
D 60°
提示1:
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正确答案:RA==
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