[求助]-两道数学题

jessiedai

On the xy-coordinate plane, what is the area of a right triangle, one side of which is defined by the points (2, 3) and (-4, 0)?

(1)   The triangle’s sides cross the y-axis at exactly two points altogether.

(2)   The y-coordinate of the third vertex of the triangle is zero

(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.

答案选B,可我觉得这道题选E. 请问SIDE是否有特指直角三角形斜边或者直角边的意思瓦?

哪位高人可以解释下(1),(2)各是什么意思.答案为什么选B呢?

If a = b开根号(根号不知道怎么输,就只好用中文拉)，what is the value of a-b?

(1)   b=3a

(2)   ab=27

(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.

答案选D, 可我觉得(1)可以有两个解: a=b=0,或者a=3,b=9. 所以 a-b的值仍然无法确定,因为有两个解,即0或者-即0或者-6.  请高人指点下迷津.还是两个解也可以接受的啊,可根据之前经验,应该唯一解才行啊,难道是我错了吗?

多谢多谢!