共50条信息
如图,在\(\triangle ABC\)中,\(AD\)为\(∠BAC\)的平分线,\(DE⊥AB\)于\(E\),\(DF⊥AC\)于\(F\).
\((1)\)若\(\triangle ABC\)面积是\(40 cm^{2}\),\(AB=12 cm\),\(AC=8 cm\),求\(DE\)的长;
\((2)\)求证:\(S_{\triangle ABD}∶S_{\triangle ACD}=AB∶AC\).
\((1)\)如图\(1\),若点\(O\)在\(BC\)上,求证:\(AB=AC\);
\((2)\)如图\(2\),若点\(O\)在\(\triangle ABC\)内部,求证:\(AB=AC\);
\((3)\)猜想,若点\(O\)在\(\triangle ABC\)的外部,\(AB=AC\)成立吗?请说明理由.
\((1)\)求证:\(AM⊥DM\);
\((2)\)若\(BC=8\),求点\(M\)到\(AD\)的距离.
如图,\(AB\)足\(⊙O\)的直径,点\(P\)在\(BA\)的延长线上,\(PD\)切\(⊙O\)于点\(C\),\(BD⊥PD\),垂足为点\(D\),连接\(BC\).
\((1)\)求证:\(BC\)平分\(∠PBD\);
\((2)\)求证:\(BC^{2}=AB·BD\).
如图,在\(\triangle ABC\)中,\(∠ABC\),\(∠ACB\)的平分线交于点\(O\),\(OD⊥BC\)于\(D\)点,\(OD=3 cm\),则点\(O\)到边\(AB\),\(AC\)的距离之和为 .
\((1)\)求证:\(AE=AF\);
\((2)\)若\(\triangle ABC\)面积是\(36 cm^{2}\),\(AB=10 cm\),\(AC=8 cm\),求\(DE\)的长.
\((2)\)若\(∠B=30^{\circ}\),\(CD=1\),求\(BD\)的长.
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