题目内容
如图,在梯形ABCD,AD∥BC,AB=CD,P为梯形内一点,且PB=PC,求证:PA=PD.
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证明:∵在梯形ABCD,AD∥BC,AB=CD,
∴∠ABC=∠DCB,
∵PB=PC,
∴∠PBC=∠PCB,
∴∠ABC-∠PBC=∠DCB-∠PCB即∠ABP=∠DCP,
又∵AB=DC,PB=PC,
∴△ABP≌△DCP.
∴PA=PD.
∴∠ABC=∠DCB,
∵PB=PC,
∴∠PBC=∠PCB,
∴∠ABC-∠PBC=∠DCB-∠PCB即∠ABP=∠DCP,
又∵AB=DC,PB=PC,
∴△ABP≌△DCP.
∴PA=PD.
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