三个梯形,高之比1:2:3,上底比6:9:4,下底比12:15:10甲面积为30...
发布网友
共1个回答
热心网友
设三个梯形的高分别为
h,2h,3h,上底分别为
6x,9x,4x,下底分别为
12y,15y,10y第一个梯形的面积S1
=
（6x+12y)h/2
=
(3x+6y)h
=
30乙梯形：S2
=
（9x+15y)*2h/2
=
(9x+15y)h丙梯形：S3
=
（4x+10y)*3h/2
=
(6x+15y)hS2
+
S3
=
(9x+15y)h
+
(6x+15y)h
=
(15x
+
30y)h
=
(3x+6y)h
*
5
=
150平方厘米
