听帝兽来历:whoever is good at English and Math, pleaz come in.

来源：百度文库 编辑：杭州交通信息网 时间：2024/05/05 02:42:08
a rectangle with a diagonal of length x is twice as long as it is wide. what is the area of the rectangle??

please explain how u did it. thank u very much! i appreciate it.

Assume that its width is a. Accordingly, the length of the rectangle is 2a.
So we can establish a mathematical equation like that:
a^2 + (2a)^2 = x
The result is: a = x/(square root 5)
Then we can make out the area of the rectangle : S = a * 2a = 0.4x^2

as the diagonal of length is twice as long as it's wide
(assume its wide is 'a', its high is 'h'.)
then a=x/2
so it's hig will be
h=sqrt(x^2-a^2)=sqrt(x^2-x^2/4)=sqrt(3)*x/2
So it's area is
S=ha=sqrt(3)*x^2/4

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