6.在四边形ABCD中,对角线+ACBD,+垂足为E,+BAC=2CAD,AQ+垂直平分-|||-BC于Q,交
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由于∠DAQ是等腰三角形的顶角,所以∠DAQ = ∠DQA = (180° - ∠DAQ)/2 = (180° - (144° - y°))/2 = (36° + y°)/2 = 18° + y°/2。根据三角形AQD的角度之和为180°,得:∠BAQ + ∠DAQ + ∠BDA = 180°y° + (18° + y°/2) + 72° = 180°3y°/2 + 90° = 180°3y°/2 = 90°3y° = 180°y° = 60°由于ABCF是平行四边形,所以∠A + ∠C = 180°。∠B - ∠A = ∠D - ∠C,即∠B - 144° = ∠D - 72°。将AB = AE + EF + FC = 3x + 2x + x = 6x带入上式,得:(∠B - 144°)(6x) = (∠D - 72°)(6x)∠B - 144° = ∠D - 72°∠B - ∠D = 72°由题目中的条件可知,BG:AE = 2:3,所以BG/AE = 2/3。可以设BG = 2a,AE = 3a。根据三角形ABC的相似性,可以得到以下比例关系:A
咨询记录 · 回答于2023-07-14
6.在四边形ABCD中,对角线+ACBD,+垂足为E,+BAC=2CAD,AQ+垂直平分-|||-BC于Q,交
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根据题目中的条件,可以得到以下几个角的关系:∠BAC = 2∠CAD∠BCA = ∠DCA∠BAC + ∠CAD + ∠BCA + ∠DCA = 360° (四边形的内角和)代入上面两个关系,得:2∠CAD + ∠CAD + ∠CAD + ∠DCA = 360°4∠CAD + ∠DCA = 360°5∠CAD = 360°∠CAD = 72°由于∠BAC = 2∠CAD,所以∠BAC = 144°。由于AQ平分BC,所以∠BAQ = ∠CAQ,而∠CAQ = ∠CAD + ∠DAQ = 72° + ∠DAQ。∠BAQ + ∠DAQ = ∠BAC = 144°∠DAQ = 144° - ∠BAQ又已知AQ平分BC,所以根据比例关系有:AQ/BQ = AQ/CQ = 3/2可以设AQ = 3x,BQ = 2x,CQ = 2x。再考虑∠DAQ = 144° - ∠BAQ,可以设∠BAQ = y°,那么∠DAQ = 144° - y°。由于∠DAQ是等腰三角形的顶角,所以∠DAQ = ∠DQA = (180° - ∠DAQ)/2 = (180° - (144°
由于∠DAQ是等腰三角形的顶角,所以∠DAQ = ∠DQA = (180° - ∠DAQ)/2 = (180° - (144° - y°))/2 = (36° + y°)/2 = 18° + y°/2。根据三角形AQD的角度之和为180°,得:∠BAQ + ∠DAQ + ∠BDA = 180°y° + (18° + y°/2) + 72° = 180°3y°/2 + 90° = 180°3y°/2 = 90°3y° = 180°y° = 60°由于ABCF是平行四边形,所以∠A + ∠C = 180°。∠B - ∠A = ∠D - ∠C,即∠B - 144° = ∠D - 72°。将AB = AE + EF + FC = 3x + 2x + x = 6x带入上式,得:(∠B - 144°)(6x) = (∠D - 72°)(6x)∠B - 144° = ∠D - 72°∠B - ∠D = 72°由题目中的条件可知,BG:AE = 2:3,所以BG/AE = 2/3。可以设BG = 2a,AE = 3a。根据三角形ABC的相似性,可以得到以下比例关系:A
根据三角形ABC的相似性,可以得到以下比例关系:AB/BC = AE/EC = 3/1设AB = 3k,BC = k由此可得AC = √(AB^2 + BC^2) = √(9k^2 + k^2) = √(10k^2) = √10 * k由于BC = k,而BC = BQ + CQ = 2x + 2x = 4x,所以k = 4x。根据比例关系可以得到:AB/BC = 3/1AB/(4x) = 3/1AB = 12x将BG = 2a,AE = 3a带入BG/AE = 2/3的比例关系,可以得到:2a/3a = 2/32a = 6aa = 1所以BG = 2a = 2,AE = 3a = 3。综上所述,在已知条件下,线段AB的长度为12x,而x = BC/4 = k/4 = 4k/4 = k。所以AB = 12k = 12 * BC因此,线段AB的长度等于线段BC的长度的12倍。
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