中一的數學問題

Let 10 and 7 cm be the length and the width of rectangle ABCD respectively.
Because BE:EC=1:1,
therefore EC = 10/2 = 5

Area of triangle CDE = (7 x 5 )/2 = 17.5
Area of rectangle ABCD = 10 x 7 = 70

Area of triangle CDE / Area of rectangle ABCD = 17.5 / 70

Area of triangle CDE : Area of rectangle ABCD = 1 : 4

2008-02-21 20:06:52 補充：
SOR...triangle : rectangle = 4:1

2008-02-21 20:59:30 補充：
我也亂了...我計出黎就 1:4 諗幅圖就 4:1 唔知點好...你自己決定吧

Let 2x be the length of BC, then BE=x, EC=x,
Let y be the length of AB, then AB=DC=y,

Area of ABCD=2xy,
Area of CDE=1/2xy

So,
Area of CDE: Area of ABCD = 1/2xy : 2xy
= 1/2 : 2
= 1 : 4

why you mentioned AB:DC=1:1 twice , is any problems?

BE:EC=1:1
AB:DC=1:1
AB:DC=1:1,
CDE:ABCD=1:1