练习题--平行线的判定方法
![](https://wkrtcs.bdimg.com/rtcs/image?w=288.00&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_2","w":"288.00","h":"138.00","dataType":"png","c":"word/media/image1.png","imgOriW":272,"imgOriH":130})
1．如图（1），若∠1=∠2，则
2．如图（2）
如果∠1=∠A，那么 ∥ ；
如果∠1=∠F，那么 ∥ ；
如果∠FDA+∠A=180°，那么 ∥ 。
![](https://wkrtcs.bdimg.com/rtcs/image?w=106.00&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_3","w":"106.00","h":"110.00","dataType":"png","c":"word/media/image4.png","imgOriW":106,"imgOriH":110})
3．如图（3），若![](https://wkrtcs.bdimg.com/rtcs/image?w=9.33&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_4","w":"9.33","h":"18.67","dataType":"gif","c":"word/media/image5.gif"})
⊥，⊥，那么a和平行吗？为什么？
答：a______b
理由是: ∵⊥，⊥
∴∠ =∠ =900
∴ ∥ （ _____________，两直线平行）
4、如图(5)，已知∠3=115º，∠2=65º，问直线a、b平行？
![](https://wkrtcs.bdimg.com/rtcs/image?w=161.33&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_3","w":"161.33","h":"141.33","dataType":"gif","c":"word/media/image6.gif"})
解：∵∠3和∠4是对顶角
∴ ∠4=∠3=115º（ 相等）
∵∠2=65º
∴∠2+∠4= + =
∴a∥b（ ，两直线平行）
巩固拓展：
1．如图，E在AB上，F在DC上，G是BC延长线上的一点：
![](https://wkrtcs.bdimg.com/rtcs/image?w=179.80&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_3","w":"179.80","h":"132.71","dataType":"png","c":"word/media/image7.png","imgOriW":168,"imgOriH":124})
（1）由∠B=∠1 可以判断直线 ∥ ，
根据是 ；
（2）由∠1=∠D 可以判断直线 ∥ ，
根据是 ；
（3）由∠A+∠D=180º可以判断直线 ∥ ，
根据是 ；
（4）由AD∥BC、EF∥BC可以判断直线 ∥ ，
根据是 ；
![](https://wkrtcs.bdimg.com/rtcs/image?w=185.00&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_2","w":"185.00","h":"108.00","dataType":"png","c":"word/media/image8.png","imgOriW":185,"imgOriH":108})
2．如图，点E在AC的延长线上，下列条件中能判断AB∥CD
的是（ ）
A.∠3=∠4 B.∠1=∠2
C.∠D=∠DCE D. ∠D+∠ACD=180 º
![](https://wkrtcs.bdimg.com/rtcs/image?w=223.80&md5sum=f7c39662ce050bdc47f4f390c4da6ba4&sign=48efa6dd36&rtcs_flag=2&rtcs_ver=4&l=webapp&bucketNum=447&ipr={"t":"img","r":"r_0","w":"223.80","h":"99.87","dataType":"png","c":"word/media/image9.png","imgOriW":186,"imgOriH":83})
3．如图，∠1=30 º，∠B=60 º，AB⊥AC，
（1）∠DAB+∠B等于多少度？
（2）AD与BC平行吗？AB与CD平行吗？
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