三角形测试题及答案

三角形测试题及答案SeventhGradeMathUnitTestPaperChapter7TriangleClass:Name:SeatNumber:Score:I.MultipleChoiceQuestions.(3pointsperquestion,24pointsintotal)1.Ifthelengthsoftwosidesofatriangleare4and5,therangeoftheperimetercis()A.1c9B.9c14C.10c18D.cannotbedetermined2.Inthethreeinterioranglesofatriangle()A.atleastoneisequalto90°B.atleastoneisgreaterthan90°C.itisimpossiblefortwotobegreaterthan89°D.itisimpossibleforalltobelessthan60°3.Thenumberoftrianglesintowhichann-sidedpolygonisdividedbydrawingadiagonalfromonevertexofthepolygonis()A.nB.(n-1)C.(n-2)D.(n-3)4.Thenumberofdiagonalsofann-sidedpolygonis()A.n(n-1)/2B.n(n-2)/2C.n(n-3)/2D.n(n-4)/25.DecorativeWorldsellstilesofthefollowingshapes:1square;2rectangle;3regularpentagon;4regularhexagon.Ifonlyonetypeoftileisselectedforpavingtheground,thetotalnumberoftilesavailableforselectionis()A.1typeB.2typesC.3typesD.4types6.Thestablefigureamongthefollowingshapesis()A.squareB.rectangleC.righttriangleD.parallelogram7.InFigure1,pointOisapointintriangleABC,∠A=80°,∠1=15°,∠2=40°,then∠BOCisequalto()A.95°B.120°C.135°D.cannotbedetermined8.Ifthesidesofatrianglearethreeconsecutivenaturalnumbersanditsperimetermsatisfies10m22,thenthereare()A.2B.3C.4D.5suchtrianglesII.Fillintheblanks.(2pointsperblank,38pointsintotal)1.Thethreealtitudesofanacutetriangleareallinthetriangle,andaobtusetrianglehasonealtitudeoutsidethetriangle,whilearighttrianglehastwoaltitudesthatareexactlyitssides.2.Ifthetwosidesofanisoscelestriangleare3cmand8cm,thenitsperimeteris14cm.3.Topreventthehexagonalframefromdeforming,atleastonemorewoodenstripneedstobenailed.4.IntriangleABC,if∠A=∠C=∠B,then∠A=∠B=∠C=60°,andthistriangleisequilateral.5.InFigure2,intriangleABC,AD⊥BCatpointD,BE=ED=DC,∠1=∠2,then1)ADisthealtitudeonsideBCoftriangleABC,2)ADisthemedianonsideBEoftriangleABC,and3)ADistheanglebisectorof∠AintriangleABE.6.Ifthelengthsoftwosidesofatriangleare6cmand8cm,andthelengthofthethirdsideiseven,thenthelengthofthethirdsideis10cm.7.Ifeachinteriorangleofaregularn-gonis150°,thenn=12andthesumofitsinterioranglesis1800°.8.Ifapolygonistruncatedbyoneofitsangles,thesumoftheinterioranglesofthenewpolygonformedis2520°,thentheoriginalpolygonhas10sides.III.AnswerQuestions.1.在直角三角形ABC中，已知AB=13cm，BC=12cm，AC=5cm，CD是AB边上的高，求△ABC的面积和CD的长。2.一个多边形的内角和是外角和的2倍，它是几边形？3.一个三角形的两条边相等，周长为18cm，其中一条边长为4cm，求另外两条边长。4.