(本小题满分8分)已知直四棱柱的底面是边长为a的正方形,高为,体积为V,表面积等于S.(1)当a="2,"h=3时,分别求V和S;(2)当V=12,S=32时,求的值.-七年级数学

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(本小题满分8分)已知直四棱柱的底面是边长为a的正方形,高为,体积为V,表面积等于S.(1)当a="2,"h=3时,分别求V和S;(2)当V=12,S=32时,求的值.-七年级数学

题目详情

(本小题满分8分)  
已知直四棱柱的底面是边长为a的正方形, 高为, 体积为V, 表面积等于S.
(1) 当a =" 2," h = 3时,分别求VS
(2) 当V = 12,S = 32时,求的值.
题型:解答题难度:中档来源:不详

答案


(1)32
(2)

(1) 当a =" 2," h = 3时,
V =" " a2h=" 12" ;       
S =" 2a2+" 4ah ="32 "  .                                --- 4分
(2) ∵a2h=" 12,"  2a(a + 2h) =32,
, (a + 2h) =,
===.                            --- 4分

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