共50条信息
\((1)\)如图\(①\),若\(BC\)为\(⊙\)\(O\)的直径,\(AB\)\(=6\),求\(AC\),\(BD\),\(CD\)的长;
\((2)\)如图\(②\),若\(∠\)\(CAB\)\(=60^{\circ}\),求\(BD\)的长.
如图,已知\(AB\)是\(⊙O\)的直径,点\(C\)在\(⊙O\)上,过点\(C\)的直线与\(AB\)的延长线交于点\(P\),\(AC=PC\),\(∠COB=2∠PCB\).
如图,边长为\(4\)的正方形\(ABCD\)外切于\(⊙O\),切点分别为\(E\)、\(F\)、\(G\)、\(H.\)则图中阴影部分的面积为_____.
\((1)\)求证:\(EF\)是\(⊙O\)的切线;
\((2)\)求证:\(AC^{2}=AD·AB\);
\((3)\)若\(⊙O\)的半径为\(2\),\(∠ACD=30^{\circ}\),求图中阴影部分的面积.
如图,已知直线\(MN\)交\(⊙O\)于\(A\)、\(B\)两点,\(AC\)是直径,\(AD\)平分\(\angle CAM\)交\(⊙O\)于\(D\),连接\(DC\),过点\(D\)作\(DE\bot MN\),垂足为\(E\).
\((1)\)求证\(DE\)是\(⊙O\)的切线.
\((2)\)若\(\angle DCA=22.5{}^\circ \),\(DE=6\),求\(AB\)的长度.
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