推 Hurricaneger: 綜合除法 10/01 12:50
推 hero010188 : 厲害! 10/02 17:50
※ 引述《hero010188 (咖啡乾了啦)》之銘言：
: http://imgur.com/HTwaA6M
: 請教請教@@" 解不出來QQ
∠PBD = ∠PCF
=> △PBD ~ △PCF
∠PCE = ∠PBF
=> △PCE ~ △PCF
PE : PC = PF : PB
=> 6 : PC = PF : PB
=> PB : PC = PF : 6
PD : PB = PF : PC
=> 4 : PB = PF : PC
=> PB : PC = 4 : PF
=> PF = 2√6
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