With BC, one leg of △ABC, as diameter, a circle is described intersecting the hypotenuse AC at P. From P draw a tangent intersecting AB at D. Showt hat AD = BD.
With BC, one leg of △ABC, as diameter, a circle is described intersecting the hypotenuse AC at P. From P draw a tangent intersecting AB at D. Showt hat AD = BD.
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试证同底之三角形且在同平行线内其面积相等,又证明如何作一三角形令其面积等于已知之四边形.
如图,在三角形ABC中∠BAC=60°,BD平分∠ABC,交AC于D,CE平分∠ACB交AB于E,BD和CE交于F,则∠EFB=【 】
设 AD 为 ∠ABC 之中线;∠ADB 之平分线交 AB 于E,∠ADC 之平分线交AC 于F,试证 EF// BC.
若三角形的两边不等,它的对不等边的两角也必不等,并且大角必对大边.
△ABC 之边 AC 之三等分点之中,设近于 A 之点为 D,而 BC 之中点为 E时,则 AE 为 BD 所二等分.
试证: 直角三角形之弦上正方形之面积,与其他两边之平方形面积之和相等.