参考啦
思路:由AD‖BC△AEP∽△FBP,△EDQ∽△CFQ
EP/BP=AE/BF=(a/2):(b/2)=a:b
EQ/CQ=DE/CF=(a/2):(b/2)=a:b
即EP/BP= EQ/CQ 由∠PEQ=∠PEQ
△EPQ∽△EBC
所PQ/BC=EP/EB=a/(a+b)
PQ/b=a/(a+b)
PQ =ab/(a+b)
参考啦
思路:由AD‖BC△AEP∽△FBP,△EDQ∽△CFQ
EP/BP=AE/BF=(a/2):(b/2)=a:b
EQ/CQ=DE/CF=(a/2):(b/2)=a:b
即EP/BP= EQ/CQ 由∠PEQ=∠PEQ
△EPQ∽△EBC
所PQ/BC=EP/EB=a/(a+b)
PQ/b=a/(a+b)
PQ =ab/(a+b)