ï¼1ï¼è¯æï¼å 为解ACB=90度
æ以ä¸è§å½¢ACBæ¯ç´è§ä¸è§å½¢
å 为Mæ¯ABçä¸ç¹
æ以CMæ¯ç´è§ä¸è§å½¢ACBçä¸çº¿
æ以CM=BM
æ以è§MCB=è§B
å 为CMæ¯åOçç´å¾
æ以è§CDM=90度
æ以è§CDM+è§ACB=180度
æ以DMå¹³è¡BC
æ以è§MDF=è§CFD
å 为è§MDF=è§MCB=1/2弧MEF
æ以è§MDF=è§B
æ以è§B=è§CFD
æ以DFå¹³è¡AB
(2)解ï¼å 为MP/CP=1/4
æ以MP/CM=1/5
å 为OC=OM=2CM
æ以MP/OM=2/5
å 为OP=OM-MP
æ以OP/OM=3/5
æ以OP/MP=3/2
å 为DFå¹³è¡ABï¼å·²è¯ï¼
æ以è§POD=è§OME
è§PDO=è§PEM
æ以ä¸è§å½¢PODåä¸è§å½¢PMEç¸ä¼¼ï¼AA)
æ以OP/MP=DP/PE=3/2
æ以PE=2/3DP
å 为DP*PE=MP*CP
æ以2/3DP^2=4/25CM^2
æ以DP^2/CM^2=6/25
å 为DP=6åæ ¹å·2
æ以CM=10åæ ¹å·3
ï¼3ï¼è§£ï¼è®¾åOçåå¾ä¸ºR
æ以CM=2OC=2OM=2R
å 为MP/CP=y
æ以MP/CM=y/y+1
MP/R=2Y/Y+1
CM/CP=y+1/y
CP/R=2R/y+1
å 为OP=OM-MP=R-MP
æ以OP=R*(1-Y)/1+Y
OP/R=1-y/1+y
å 为OP/PM=DP/PE
æ以DP/PE=1-y/y
PE=(y/1-y)*DP
å 为MP*CP=DP*PE
æ以DP^2*(y/1-y)=4R^2*ï¼1-y)/(1+y)^2
å 为DFå¹³è¡AB(å·²è¯ï¼
æ以弧EF=弧DM
è§A=è§CDF
å 为DMå¹³è¡BCï¼å·²è¯ï¼
æ以弧DM=弧CF
æ以弧CF=弧EF
å 为è§CDF=1/2弧CF
è§EDF=1/2弧EF
æ以è§CDF=è§EDF
æ以DFå¹³åè§CDE
æ以OP/OC=OP/OC
æ以DP^2/DC^2=OP^2/OC^2
æ以CM^2/DC^2=(1-y)^2/(1+y)^2
CM^2=DC^2*((1-y)
å 为è§ACB=90度
æ以ä¸è§å½¢CDFæ¯ç´è§ä¸è§å½¢
æ以tanè§CDF=CF/DC
DF^2=CF^2+DC^2
æ以tanA=DF/DC
å 为tanA=x
æ以DF/DC=x
æ以DF=DC*x
æ以DC^2(1+x^2)=CM^2=DC^2*(1-y)
1+x^2=1-y^2
æ以y=-x^2 (0<x<1)
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