高三文科数学第七次月考试题

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锥侧

l）·

球P

(

)

C

P

P)nn n

I

,

I

,

I I

I {

}

x

(

C

(

)

(

)

(

)

(

)

n

：设

分），共

,

,

b

b

b

b

b

b

b

,,

,,

：如图，正方体ABCDABCD

，则

C

P

的最小值为

AB

CABC

OM

ON

,

MN

中，底面

分别是F E

、、

、、

n

n

n

(

b

b

b

n

n

n

n

g

b

g

EE

l

EM

N

AM

Em

m

m

A F B

/

,

解：（）：OM

ON

cos cos

nsi nsi

cos(

）：

MN

,

MN

FG

········

·································································

FG

∥

·

·················

·············

·

，所以

································

·······················

······················································

········································

·······················································································

··········································································

··············································

b

b,0),F(0,

,

)EF

).

b

),

b

).

·························································

EF

················

,0),F(0,

,1).

,

,

),····································································································

· ,- ,- )EF

EF

·

·····························

·

- ,0),

EF

·······················································································································

·······

································································

······························································

，

，。

E

），（

p

p

p

p

p

p

E

（

）

（

）

（

）

（

）（

）

解：（

n

n

(

n

n

(

n

n

(

n

n

(

n,

又由已知:

n

,

故：b

）：由已知：

/

(

)

(

,

max

）：F

g

b

F

(

)

(

+ +

：F

：F

：F

：F

b

b

b

b

时，b

,F

有一根，

故：

g

有一解。

:

b:

b

时，b

,F

有两根，

故：

g

有两解。:

b

b

时，

b

,F

有三根，

故：

g

有三解。:

b

时，b

,F(

)有两根，

故：

(

)

g

(

)有两解。:

b

时，b

,F

(

)有一根，

故：

(

)

g

(

)有一解。

.

mx

my

m

m

m

,

m n

E

l:

E

)

AM

AM

,

,

AM

AM

AM