已知曲线C1的极坐标方程为P（2cosθ+5sinθ）-4=0；曲线C2的参数方程为
求（1）曲线C1和曲线C2的普通方程 （2）曲线C1和曲线C2的位置关系． |
（1）∵曲线C1的极坐标方程为ρ（2cosθ+5sinθ）-4=0，即2ρcosθ+5ρsinθ-4=0，
∴曲线C1的普通方程为2x+5y-4=0，
∵曲线C2的参数方程为
（θ为参数），x=2cosθ y=2sinθ
∴曲线C2的普通方程为x2+y2=4，
故曲线C1和曲线C2的普通方程分别为2x+5y-4=0，x2+y2=4；
（2）由（1）可知，曲线C1是方程为2x+5y-4=0的直线，曲线C2是方程为x2+y2=4的圆，
曲线C2的圆心是（0，0），半径是r=2，
故圆心（0，0）到直线2x+5y-4=0的距离d=
=|-4| 22+52
＜r=2，4 29
∴直线与圆的位置关系是相交，
故曲线C1和曲线C2的位置关系是相交．
| 完形填空。 | |||
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| ( )1. A. hide ( )2. A. lessons ( )3. A. stone ( )4. A. hid ( )5. A. lunch ( )6. A. terrible ( )7. A. looked up ( )8. A. strange ( )9. A. goodbye ( )10. A. homeless ( )11. A. amazed ( )12. A. trick ( )13. A. learn ( )14. A. hear ( )15. A. work | B. wash B. experience B. coin B. stood B. coat B. hot B. looked around B. second B. yes B. lively B. excited B. role B. take B. understand B. refuse | C. sell C. fun C. sweet C. worked C. drink C. hard C. looked down C interesting C. hello C. careless C. pleased C. game C. forget C. remember C. advise | D. repair D. games D. clip D. rested D. shoes D. soft D. looked out D. lost D. thanks D. sick D. moved D. cards D. accept D. write D. give |