è§Bï¼è§Cï¼è§Dï¼1ï¼2ï¼3
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å è§Aï¼è§Cï¼180度 å è§A=180-è§C=180-2x
å è§Aï¼è§C+è§B+è§D=360
å 180-2x+2x+3x+x=360
解å¾x=45
åè§C=2x=2*45=90°
å è§A=180-è§C=90°
å边形å
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å
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å¿ â´â CDE=50°