题目

如图所示，CD⊥AB ,垂足为D,∠ACB=90°,∠A=30°. 求证：BD=AB 答案：证明：∵∠A=30°，∠ACB=90° ∴∠B=60°，BC=AB                                           又∵CD⊥AB ∴∠BDC=90° ∴∠BCD=30°                                                    ∴BD=BC =×AB =AB                                                      

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