2022高中牛津英语周报第13期答案

22,(本小题满分12分)解:(1)设M(x,y),由题意得,MO⊥AO,所以MO O4(=M4上……1分因为圆M的半径为r=y 2=MA|,|AO=2所以x2 y2 4=(y 2),高2分化简得M的轨迹C的方程为x2=4y3分(2)(i)由(1)知:曲线C为:y==,设f(x)=则f(x)=2设圆H与曲线C的公共点为r(2)(>0),则曲线C在T的切线l斜率k=f(0)=由题意,直线1与圆W相切于T点,设圆W的标准方程为:(x-a)2 y2=2(a>0),则直线WT的斜率k=-412t-a 4(t-a)因为l⊥WT,所以1,即r 8(t-a)=024(t-a)又因为(-0)()2=2,所以(-) (.)=2,所以 4 -128=05分令2=2,则23 42-128=0,所以(花3-42) (822-128)=0即(λ-4X2 82 32)=0,所以2=4所以t=2,a=3从而圆F的标准方程为:(x-3)2 y2=27(ⅱ)设E(x,片),F(x2,y2),直线l2:y=-x y=-x Imx2=4y得:x 4x-4m=0,所以 =4,=一4所以=√x x2)-4x2=42 m又因为|P=2,2-cm=313=√2m2 12m-10所以4√2(1 m)1 mPQ√-2m2 12m-10分2 6w-5由于l2与曲线C、圆均有两个不同的交点,解得1

ear jonaIm glad to hear from you and i d like to share withyou something about serving chopsticksi As you know, people in China are encouraged to useserving chopsticks, which are different from personal chopticks in shape and colour serving chopsticks are used totake food from shared dishes. You can add food to yourbowl with them, but never place them into your mouth oryour own bowlUsing serving chopsticks benefits everyone at tableFirst of all, it prevents diseases from' spreading while weare eating together. We can also use them to put food intoothers bowls, thus creating a pleasant and harmoniousdining atmosphereHoping you'l come to China to experience themfirst handYoourL i hua

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