如图,三角形abc中,ab=ac=6,bc=9,点p,d分别在边bc,ad上,联结ap,pd,若bp=4,角apd=角b.求cd长;pd平行于ab

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如图,三角形abc中,ab=ac=6,bc=9,点p,d分别在边bc,ad上,联结ap,pd,若bp=4,角apd=角b.求cd长;pd平行于ab
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如图,三角形abc中,ab=ac=6,bc=9,点p,d分别在边bc,ad上,联结ap,pd,若bp=4,角apd=角b.求cd长;pd平行于ab
如图,三角形abc中,ab=ac=6,bc=9,点p,d分别在边bc,ad上,联结ap,pd,若bp=4,角apd=角b.求cd长;pd平行于ab

如图,三角形abc中,ab=ac=6,bc=9,点p,d分别在边bc,ad上,联结ap,pd,若bp=4,角apd=角b.求cd长;pd平行于ab
⑴∵∠B+∠APB+∠BAP=180°,∠APB+∠APD+∠CPD=180°,∠B=∠APD,
∴∠BAP=∠DPC,
∵AB=AC,∴∠B=∠C,
∴ΔABP∽ΔPCD,
∴AB/PC=PB/CD,PC=BC-BP=5,
∴CD=10/3,
⑵∵CP/CB=5/9,CD/CA=(10/3)/6=5/9,
∴CP/CB=CD/CA,又∠C=∠C,
∴ΔCPD∽ΔCBA,
∴∠CPD=∠B,
∴PD∥AB.