共50条信息
如图,\(AB\)为\(⊙O\)直径,\(C\)、\(D\)为\(⊙O\)上不同于\(A\)、\(B\)的两点,\(∠ABD=2∠BAC\),连接\(CD.\)过点\(C\)作\(CE⊥DB\),垂足为\(E\),直线\(AB\)与\(CE\)相交于\(F\)点.
\((1)\)求证:\(CF\)为\(⊙O\)的切线;
\((2)\)当\(BF=5\),\(\sin F=\dfrac{3}{5}\)时,求\(⊙O\)的半径.
如图,\(AB\)为圆\(O\)的直径,点\(C\)为圆\(O\)上任意一点,\(OD/\!/AC\),\(AD=OC\).
\((1)\)求证:四边形\(OCAD\)是平行四边形;
\((2)\)填空:\(①\)当\(∠B=\)______\({\,\!}^{\circ}\)时,四边形\(OCAD\)是菱形;
\(②\)当\(∠B=\)______\({\,\!}^{\circ}\)时,\(AD\)与圆\(O\)相切.
进入组卷