?$證明：(1)因?yàn)槲暹呅蜛BCDE是正五邊形，$?
?$所以AB=BC，\angle ABM= \angle BCN.$?
?$因?yàn)樵赲triangle ABM與\triangle BCN中，$?
?$AB=BC，\angle ABM=\angle \mathit{B}\mathit{C}\mathit{N}，BM=\mathit{C}\mathit{N}，$?
?$所以\triangle ABM≌\(chéng)triangle BCN.$?
?$(2)因?yàn)閈triangle ABM≌\(chéng)triangle BCN，$?
?$所以\angle MBP= \angle BAP.$?
?$因?yàn)閈angle MBP+ \angle BMP+ \angle BPM= \angle BAP+ \angle BMA+ \angle MBA=180^{ \circ }，$?
?$所以\angle BPM= \angle MBA，$?
?$所以\angle APN= \angle MBA，$?
?$所以\angle MBA=\angle APN=\dfrac{(5-2)\times 180}{5}={108}^{\circ }.$?
