解答题-证明题 适中0.65 引用1 组卷799
完成证明并写出推理根据:
已知,如图,∠1=132o,∠
=48o,∠2=∠3,
⊥
于
,
求证:
⊥
.
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/2ac63b55ebdf43eb9646a17f4f1ee3d0.png)
证明:∵∠1=132o,∠ACB=48o,
∴∠1+∠ACB=180°
∴DE∥BC
∴∠2=∠DCB(____________________________)
又∵∠2=∠3
∴∠3=∠DCB
∴HF∥DC(____________________________)
∴∠CDB=∠FHB.(____________________________)
又∵FH⊥AB,
∴∠FHB=90°(____________________________)
∴∠CDB=________°.
∴CD⊥AB.(____________________________)
已知,如图,∠1=132o,∠
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/a2930c4589b74c25bac582031c5a50ac.png)
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/8c80274018924338bb293cb593232f8c.png)
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/e8c2f3a427704933a100de47bb23b043.png)
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/c8cd9465723e45f89800468e35e2f245.png)
求证:
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/e52b6f97f50147f4b04b56f1a27b723f.png)
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/e8c2f3a427704933a100de47bb23b043.png)
![](https://img.xkw.com/dksih/QBM/2015/6/25/1573853802455040/1573853808680960/STEM/2ac63b55ebdf43eb9646a17f4f1ee3d0.png)
证明:∵∠1=132o,∠ACB=48o,
∴∠1+∠ACB=180°
∴DE∥BC
∴∠2=∠DCB(____________________________)
又∵∠2=∠3
∴∠3=∠DCB
∴HF∥DC(____________________________)
∴∠CDB=∠FHB.(____________________________)
又∵FH⊥AB,
∴∠FHB=90°(____________________________)
∴∠CDB=________°.
∴CD⊥AB.(____________________________)
14-15七年级下·山东德州·期中
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