2015-2016年盐城市盐都区七年级下第一次段考数学试卷含答案解析  
7．若多边形的边数增加1，则其内角和的度数（　　）                                  
A．增加180°             B．其内角和为360°                                         
C．其内角和不变         D．其外角和减少                                            
【考点】多边形内角与外角．                                                                   
【分析】根据多边形的内角和公式（n﹣2）180°列式求解即可．                      
【解答】解：是多边形的边数为n，                                                         
则原多边形的内角和为（n﹣2）180°，                                                     
边数增加后的多边形的内角和为（n+1﹣2）180°，                                          
∴（n+1﹣2）180°﹣（n﹣2）180°=180°，                                                
∴其内角和的度数增加180°．                                                                  
故选A．                                                                                             
【点评】本题考查了多边形的内角和公式，熟记公式是解题的关键．