题目

已知方程x2＋y2－2(t＋3)x＋2(1－4t2)y＋16t4＋9＝0(t∈R)的图形是圆． (1)求t的取值范围； (2)求其中面积最大的圆的方程； (3)若点P(3,4t2)恒在所给圆内，求t的取值范围． 答案：解析] (1)方程即(x－t－3)2＋(y＋1－4t2)2 ＝－7t2＋6t＋1， ∴r2＝－7t2＋6t＋1>0.∴－<t<1. (2)∵r＝ ∴t＝时，rmax＝， 此时圆面积最大，所对应的圆的方程得  (3)当且仅当32＋(4t2)2－2(t＋3)×3＋2(1－4t2)(4t2)＋16t4＋9<0时，点P在圆内． ∴8t2－6t<0，即0<t<.7．An evil man once went to a wise man asking for advice about starting a new life．The wise man asked him to give up at least one of his（36）Ahabits．He gave up telling lies．That night，when he went to the loyal palace to（37）Bsomething，he found in the palace another person，who said he was a thief．He too（38）Cthat he was a thief and both（39）Dthe treasury （国库）and（40）Bbetween themselves the diamonds found there．The other person was none other than the king，he（41）Ato be a thief．While the diamonds were shared，the real thief（42）Cthe king who was losing his entire stock，he asked his（43）Dto leave one diamond behind in the safe．And，it was done．The next morning，when it was（44）Bthat the treasury had been broken into，the Minister was sent by the king to assess the（45）A．The Minister found the diamond，thinking that it had（46）Cthe eyes of the thieves．He（47）Ahid it in his own pocket and reported at the court that all the diamonds were（48）B!The king had got from the real thief his address the previous night while they（49）Awith their separate bags．So he（50）Chim and when the thief stood in court before the king，he admitted that（51）Dbut one of the diamonds were stolen by him and his（52）Ccompanion．The diamond was discovered in the pocket of the Minister and the king dismissed（免…的职） him for the（53）B．The real thief was appointed Minister（54）A，and he gave up his other bad habits too．It is a perfect（55）Dof how one step in the right direction can lead to another．36．A．badB．regularC．socialD．unfortunate37．A．returnB．stealC．collectD．exchange38．A．learnedB．suggestedC．announcedD．heard39．A．set upB．looked intoC．rang upD．broke into40．A．hidB．dividedC．rewardedD．treated41．A．pretendedB．expectedC．hopedD．appeared42．A．looked down uponB．agreed withC．felt pity forD．knocked into43．A．conductorB．neighborC．friendD．companion44．A．saidB．discoveredC． recordedD．believed45．A．lossB．costC．priceD．number46．A．attractedB． keptC．missedD．filled47．A． suddenlyB．carefullyC．firmlyD．quietly48．A．soldB．goneC．damagedD．packed49．A．partedB．practicedC．workedD．rested50．A．waited forB．called onC．sent forD．thought of51．A． bothB．someC．noneD．all52．A．impatientB．unknownC．homelessD．disabled53．A．puzzleB．mistakeC．lieD．excuse54．A．insteadB．indeedC．tooD．though55．A．matchB．experienceC．experimentD．example