角平分线在几何计算中应用与折叠问题.pdfVIP

Specialtraining:Cleveruseoftherelevant

calculationoftheanglebisector

Famousteacherdotgold:Thedefinitionofananglebisectorisanimportantbasisforanglecalculations.Therefore,to

solvethistypeofproblem,wemustfindthequantitativerelationshipofangfromtheanglebisector,usethepositional

relationshipofequalanginthefigure,andsolveitincombinationwiththesumanddifferencerelationshipsofang.

Angleproblemweenanglebisectors(classification

discussionideas)

1.Itisknownthat∠AOB＝100°,∠BOC＝60°,OMdivides∠AOB,ONdivides∠

BOC,andfindthedegreeof∠MON.

Cleverlyuseanglebisectorstosolvethefolding

problem(foldingmethod)

2.Asshowninthefigure,foldarectangularpieceofpaperdiagonallysothatthevertexA

fallsatA′andBCisacrease,thenfoldBEtofallonthestraightlinewhereA′Bislocated.The

creaseisBD.SowhatistheangleweenthetwofoldsBCandBD?

(Question2)

巧用角平分线解决角的和、差、倍、分问

题（方程思想）

3.如图，已知∠COB＝2∠AOC，OD平分∠AOB，且∠COD＝19°，求∠AOB的度数.

（第3题）

巧用角平分线解决角的推理说明问题

（转化思想）

4.如图，已知OD，OE，OF分别为∠AOB，∠AOC，∠BOC的平分线，∠DOE和∠COF

有怎样的关系？说明理由.

（第4题）

Cleverlyuseanglebisectorstosolvethesum,difference,

multipleandfractionofang

Question(Equation

Thought)