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【323612】2023七年级数学上册 第4章 图形的初步认识4.6 角4.6.2角的比较和运算课时练

时间:2025-01-15 19:27:11 作者: 字数:3736字
简介:


角的比较和运算

(30分钟 50)

一、选择题(每小题4,12)

1 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> .如图,∠1=∠2,∠3=∠4,则下列结论正确的个数是(  )

AD平分 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>BAF;

AF平分∠BAC;

AE平分∠DAF;

AF平分∠DAC;

AE平分∠BAC.

A.4    B.3    C.2     D.1

2.如图,OC是∠AOB的平分线,OD平分∠AOC,若∠COD=25°,则∠AOB的度数为

(  )

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>

A.100° B.80°

C.70° D.60°

3 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> .如图所示,将一张长方形纸的一角斜折过去,使顶点A落在A',BC为折痕,如果 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> BD为∠ABE的平分线,则∠CBD= (  )

A.80° B.90° C.100° D.70°

二、填空题(每小题4,12)

4 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> . <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>,O为直线AB上一点,OD平分∠AOC,OE平分∠BOC,则∠DOE=_______°;若∠AOD=30°,则∠DOC=_______°,∠COE=_______°,∠BOE=_______°,∠BOD=_______°.

5.已知∠AOB=60°,OC是∠AOB的一条三等分线,则∠AOC=________.

6.若∠A=20°18',∠B=20.25°,则∠A________∠B(填“>”“<”或“=”).

三、解答题(26)

7.(8)(佛山中考)比较两 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> 角的大小,有以下两种方法(规则):

用量角器度量两个角的大小,用度数表示,则度数大的角大;

构造图形,如果一个角包含(或覆盖)另一个角,则这个角大.对于如图给定的∠ABC与∠DEF,用以上两种方法分别比较它们的大小.:构造图形时,作示意图(草图)即可.

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>

8 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> .(8)如图,BD平分∠ABC,BE分∠ABC2∶5两部分, <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠DBE=21°,求∠ABC的度数.


【拓展延伸】

9.(10)(1)如图所示,已知∠AOB是直角,∠BOC=30°.OM平分∠AOC,O <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> N平分

BOC,求∠MON的度数.

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>

(2)如果(1)中∠AOB=α,其他条件不变,求∠MON的度数.

(3)如果(1)中∠BOC=β(β为锐角),其他条件不变,求∠MON的度数.

(4)你从(1)(2)(3)的结果中能发现什么规律?















答案解析

1.【解析】选C.因为∠1=∠2,所以AE平分∠DAF,故③正确.又因为∠3=∠4,所以∠1+∠3=∠2+∠4,即∠BAE=∠CAE,所以AE平分∠BAC.故⑤正确.

2.【解析】选A.因为OC是∠AOB的平分线,

所以∠AOC=∠COB.因为OD是∠AOC的平分线,

所以∠AOD=∠COD.

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> 为∠COD=25°,所以∠AOC=2∠COD =50°,

所以∠AOB=2∠AOC =100°.

3.【解析】选B.因为将顶点A折叠落在A',所以∠ABC=∠A'BC,

又因为BD为∠ABE的平分线,所以∠ABD=∠DBE,因为∠ABC+∠A'BC+∠ABD+

DBE=180°,所以∠CBD=90°.

4.【解析】因为OD平分∠AOC,OE平分∠BOC,所以∠AOD=∠COD, <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠COE=∠BOE.又因为∠AOD+∠COD+∠COE+∠BOE=180°,所以∠DOE=90°;因为∠AOD=30°,所以∠COD=∠AOD=30°,所以∠COE=60°,∠BOE=60°,∠BOD=150°.

答案:90 30 60 60 150

5.【解析】因为OC是∠AOB的三等分线,所以∠AOC= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠AOB或∠BOC= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠AOB <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ,所以∠AOC= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> 20°或∠BOC=20°,所以∠AOC=20°40°.

答案:20°40°

6.【解析】因为18×( <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> )°=0.3°,

所以∠A=20°18'=20.3°>20.25°,所以∠A>∠B.

答案:>

7.【解析】①用量角器度量∠ABC=50°,∠DEF=70°,

即∠DEF>∠ABC.

如图:

 <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>

把∠ABC放在∠DEF,使顶点BE重合,EFBC重合,EDBAEF的同侧,从图形可以看出∠DEF包含∠ABC,即∠DEF>∠ABC.

8.【解析】因为BD平分∠ABC,

所以∠ABD=∠CBD,

因为BE分∠ABC2∶5两部分,设∠ABE=2x°,

则∠E <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> BC=5x°,∠ABC=7x°,所以∠ABD=3.5x°.

因为∠DBE=21°,所以3.5x-2x=21,解得x=14,

所以∠ABC=14°×7=98°.

9.【解析】(1)∠MON=∠COM-∠CON= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠AOC- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠BOC= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ×120°- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a>  <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ×30°=45°.

(2)∠MON=∠COM-∠CON= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠AOC- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠BOC= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> (α+30°)- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ×30°= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> α.

(3)∠MON=∠COM-∠CON= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠AOC- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> ∠BOC= <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> (90°+β)- <a href="/tags/16/" title="课时" class="c1" target="_blank">课时</a> <a href="/tags/29/" title="初步" class="c1" target="_blank">初步</a> <a href="/tags/42/" title="图形" class="c1" target="_blank">图形</a> <a href="/tags/53/" title="认识" class="c1" target="_blank">认识</a> <a href="/tags/55/" title="数学" class="c1" target="_blank">数学</a> β=45°.

(4)∠MON的大小等于∠AOB的一半,而与∠BOC的大小无关.

4

《【323612】2023七年级数学上册 第4章 图形的初步认识4.6 角4.6.2角的比较和运算课时练.doc》
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