10. 已知面积为S的凸四边形中,四条边长分别记为a
1 , a
2 , a
3 , a
4 , 点P为四边形内任意一点,且点P到四边的距离分别记为h
1 ,
h2 , h
3 , h
4 , 若
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=
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=
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=
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=k,则h
1+2h
2+3h
3+4h
4=
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类比以上性质,体积为y的三棱锥的每个面的面积分别记为S
l , S
2 , S
3 , S
4 , 此三棱锥内任一点Q到每个面的距离分别为H
1 , H
2 , H
3 , H
4 , 若
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=
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=
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=
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=K,则H
1+2H
2+3H
3+4H
4=( )