Question

如图，直线AB，CD相交于点O，因为∠1+∠3=180°，∠2+∠3=180°，所以∠1=∠2．其推理依据是（　　）              

                                                                         

A．同角的余角相等     B．等角的余角相等                                        

C．同角的补角相等     D．等角的补角相等                                        

Answer 1

D【考点】余角和补角．                                                                          

【分析】根据题意我们由∠1与∠2的补角相等，得出∠1=∠2．                    

【解答】解：∵∠1与∠2的补角相等，                                                  

∴∠1=∠2（等角的补角相等）．                                                            

故选D．                                                                                            

【点评】本题考查了补角的知识，注意同角或等角的补角相等，在本题中要注意判断是“同角”还是“等角”．