广东省2024-2025学年七年级开学测试试题(数学)

广东省2024-2025学年七年级开学测试试题(数学)试卷答案,我们目前收集并整理关于广东省2024-2025学年七年级开学测试试题(数学)得系列试题及其答案，更多试题答案请关注本网站↓↓↓

广东省2024-2025学年七年级开学测试试题(数学)试卷答案

以下是该试卷的部分内容或者是答案亦或者啥也没有，更多试题答案请捕获只因

阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项

AYellowstoneNationalParkYellowstoneisopenyear-roundtovisitors,thoughexperiencesdifferdependingontheseasonyouvisit.March-May:SnowcancontinuctofallintoMarchandmanyoftheroadsmayremainclosed,withploughingusuallybeginningsometimeinApril.Hikingconditionsatthistimearewet.Youwon'tfindmanycrowds,forgoodreason.June-August:ThebusiesttimeofyearintheparkisJulyandAugust,asfamiliesarriveintheirdrovesandtemperaturesriseupintothemid-20s(C).Backcountrytrailsarefullyopenandthisistheidealtimetogohiking.September-October:BySeptember,theweatherisprettymild(highsof19CinSeptember).Bearscanbespottedbyroadsideastheytrydesperatelytofattenupbeforewinter.November-February:Temperaturcscandropbelowzcro,butthisalsoyicldssomeuniquccxperiences.Elkandbisonarealreadymigratinginimpressiveherdsandthisisagreattimeforwolfspotting-theirdarkcoatsaremucheasiertoseeagainstawhitebackdropofsnow.Wolf-trackingtripsareamust.CostoftravelEntrancefeesforYellowstoneareE16forindividualsandanadditionalf30foracar.Campsitesvaryinprice,costingaslittleasE12.50pernight.AccommodationDuringthepeaksummermonths,pricesriseandroomsarebookeduplonginadvance.Inwinterjustahandfulofthepark'slodgesremainopen21.Whereisthistextprobablytakenfrom?A.Arescarchreport.B.Asciencenewspaper.C.Atravelbrochure.D.Ageographytextbook.22.WhichmonthismostsuitableforhikinginYellowstoneNationalPark?A.July.B.April.C.October.D.November.23.Howmuchshouldacoupledrivingacarpayforentrancefees?A.f46.B.f44.5.C.32.D.f62.BFromhisuptownManhattanhome,SamirKumarcanusuallyseeskyscrapersdowntown.Butthisweck,assmokefromwildfiresraginginthewesternUnitedStatesandCanadastretchedallthewaytotheEastCoast,thecityskylinewasinvisible.

分析先求出圆的参数方程，利用参数方程结合三角函数的性质能求出x²+y²的最大值．

解答解：∵实数x，y满足x²+y²-6x+8y+24=0，
x²+y²-6x+8y+24=0圆，圆心为（3，-4），半径为：r=$\frac{1}{2}\sqrt{36+64-96}$=1，
∴$\left\{\begin{array}{l}{x=3+cosθ}\\{y=-4+sinθ}\end{array}\right.$，0≤θ＜2π，
∴x²+y²=（3+cosθ）²+（-4+sinθ）²=-8sinθ+6cosθ+26=10sin（θ+α）+26，
∴x²+y²的最大值为36．
故答案为：36．

点评本题考查代数式的最大值的求法，是基础题，解题时要认真审题，注意圆的参数方程的合理运用．