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楼主
发表于 2019-11-15 20:21:47 | 只看该作者 回帖奖励 |倒序浏览 |阅读模式
  If the lengths of the legs of a right triangle are integers, what is the area of the triangular region?
(1)The length of one leg is 3/4 the length of the other.
(2)The length of the hypotenuse is 5.
<2>为什么可以  
我按照5,12,13 或者9 40 41 比例配出来5
What is the length of the hypotenuse of △ABC?

(1)The lengths of the three sides of △ABC are consecutive even integers .
(2)The hypotenuse of △ABC is 4 units longer than the shorter leg.

这个2 为什么又不行

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沙发
发表于 2019-11-15 20:30:32 | 只看该作者
第一个说了直角边都是整数,第二个没说
板凳
 楼主| 发表于 2019-11-15 21:18:59 | 只看该作者
那单独看第二题的2为啥不行呢 6 8 10?
地板
发表于 2019-11-15 22:38:42 | 只看该作者
Let's denote three sides by x,y,z. (z stands for hypotenuse)

Question: whether xy is solved uniquely

(1) x=3a  y=4a  xy=12a^2    the value of xy depends on a

(2) x^2+y^2 = 25  where x, y are integers. Notice that x and y share the same position, we can simply let x<=y<5 and it does not affect the value of xy .

x=1 , y_max = 4,  x^2+y^2 = 17  Not satisfied.

x=2, y_max =4   Not satisfied.

x=3,y_max= 4    Bravo.

x=4, y_max = 4  Not satisfied. (As I mentioned above, the case x=3,y=4 and another case x=4, y=3 can be viewed as the same thing because of the same position of x and y, therefore, the value of xy does not change.)

Under Statement 2, we have unique value of xy, which is 12.
5#
发表于 2019-11-17 19:43:24 | 只看该作者
求楼主分享300难题数学部分的题感激不尽!
6#
 楼主| 发表于 2019-11-26 09:07:34 | 只看该作者
可以在gmatla做,CD 的怎么说有必出老师的网
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