[求助]OG11第11题(PDF)

treepple

11. In ΔPQR, if PQ = x + 2, and PR = y, which of the three angles of ΔPRQ has the greatest
degree measure?
(1) y = x + 3
(2) x = 2
Explanation:
In any triangle, the largest angle is opposite the longest side. To determine the longest side it
suffices to determine whether y > x + 2. Since x + 3 > x + 2, it follows from (1) that y > x + 2.
Statement (1) alone is therefore sufficient. From (2) it follows that PQ = 2 and QR = 4. Thus, y can
be any value between 2 and 6; it follows that y > x, but it cannot be concluded that y > x + 2.
Statement (2) alone is therefore not sufficient. Therefore, statement (1) ALONE is sufficient, but
statement (2) alone is not sufficient to answer the question.

我觉得答案应该是C啊，因为第一个条件不充分，因为不能确定第三条边，所以自然不能确定最大角，第二个条件不能确定Y，但两个条件和在一起的话就可以得出三条边的长度，也就是最大角了，大家的看法呢？

treepple

sorry，我现在觉得是E了，因为两个即使和在一起也不能推出第三条边。。。。。。。。

treepple

补充一下选项：

A. statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the
question asked;
 B. statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the
question asked;
 C. BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but
NEITHER statement ALONE is sufficient;
 D. EACH statement ALONE is sufficient to answer the question asked;
 E. statements (1) and (2) TOGETHER are NOT sufficient to answer the question asked, and
additional data specific to the problem are needed

treepple

俺一朋友说的，但俺还是没看懂

when u say C, you know PR =5 and PQ = 4 from those two statments,, but no angle involve so far
 from statement 1 alon, you know relationship between and y, so good for resolve
 from statement 2 alone, you know x only, no relationship between x and y, so not good for resolve

you know relationship between x and y, so good for resolve, so you know y=5 and x=2

treepple

没人给我解答阿

treepple

原来题目是if PQ=X,QR=X+2 AND PR=y，偶晕。。。谢谢780NN告知真相