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(2002•佛山)如图,直线AB切⊙O于点A,割线BDC交⊙O于点D、C.若∠C...
(2002•佛山)如图,直线AB切⊙O于点A,割线BDC交⊙O于点D、C.若∠C=30°,∠B=20°,则∠ADC=( )
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A.70°
B.50°
C.30°
D.20°
考点分析:
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