Question

如圖所示，求∠A+∠B+∠C+∠D+∠E+∠F+∠G的度數(shù)是______．

Answer 1

連接BE．
在△CDM與△BEM中，∠CMD=∠BME，
∴∠C+∠D=∠CBE+∠DEB，
∴在五邊形ABEFG中∠A+∠ABC+∠C+∠D+∠DEF+∠F+∠G
=∠A+∠ABC+∠CBE+∠DEB+∠DEF+∠F+∠G
=∠A+∠ABE+∠BEF+∠F+∠G
=（5-2）•180°
=540°．