问题
填空题
已知点A(-1,0),B(1,0),点P(x,y)满足(x-3)2+(y-4)2=4,则|
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答案
∵P(x,y)满足(x-3)2+(y-4)2=4,
则P点的坐标可表示为x=3+2cosa,y=4+2sina
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|2+|PA
|2=[(4+2cosa)2+(4+2sina)2]+[(2+2cosa)2+(4+2sina)2]PB
=[16+16cosa+4cos2a+16+16sina+4sin2a]+[4+8cosa+4cos2a+16+16sina+4sin2a]
=(32+4+16cosa+16sina)+(20+4+8cosa+16sina)
=60+24cosa+32sina
=60+8(3cosa+4sina)
=60+8[5sin(a+b)]>=60+8×(-5)=20
则|
|2+|PA
|2的最小值是20PB
故答案为:20