有

sin2(θ/2)/e12+cos2(θ/2）/e22=1

即

-2sin2(θ/2)/e13

/

-1/e12

=

-2cos2(θ/2）/e23

/

-1/e22

即

sin2(θ/2)/e1

=

cos2(θ/2）/e2

即

e1=tan2(θ/2)e2

即

cos^4(θ/2)/(sin2(θ/2)e22)

+

cos2(θ/2）/e22

=

1

即

cos2(θ/2）/(sin2(θ/2)e22)=1

即

e2=cot(θ/2)

e1=tan(θ/2)

且

0＜θ/2＜π/2

即

tan(θ/2)＞sin(θ/2)

恒成立

即

e1＞sin(θ/2)

恒成立

即

原式

1/e1+1/e2

恒有

最大值

cot(θ/2)+tan(θ/2)

=

cos(θ/2)/sin(θ/2)+sin(θ/2)/cos(θ/2)

=

cos2(θ/2)+sin2(θ/2)

/

sin(θ/2)cos(θ/2)

=

1

/

sin(θ/2)cos(θ/2)

=

2

/

2sin(θ/2)cos(θ/2)

=

2/sinθ

得證

ps.

有關(guān)

這條

發(fā)視頻的

無恥行徑

詳見

CV7804148