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295. A triangle is on the xy plane, with coordinates A, B, and C. B and C coordinates are given on the plane. What is the coordinate of A? 1) AB=x 2) BC=y (x and y are given as numbers, but I forgot them all!!) (Just try to image or learn the concept)
from 1) A点在以B为圆心x为半径的圆上 无法确定哪个点 not A
from 2) 只能求出BC的长度, 无法确定A点 not B
union: 不能确定A点 so E
没看懂题目
296. Is n a prime number? 1) n is a factor of 125 2) n is a factor of 75
遇到这种题 直接选E, 如果你能通过任何条件能判定一个数是不是素数, 你就能证明1 + 1 = 2 了
297. 3x-4y>0, is x>y? 1) x= 1 2) y=2 : (數字不確定)
3x – 4y > 0 x > 4/3y
from 1) x > y + 1/3y, x – y > 1/3y, when y > 0 x – y > 0; when y < 0 x = 1 > 0 > y
from 2) 属于1) 中 y > 0的情况
so D
298. (1/8)^2 (这题用分数算, 答案全是分数的形态): Answer(0.25)^3
这不就是 1/8 * 1/8 = 1/64 淡定。。。。
299. Given a rectangle, with sides PQRS. The area is 4根号3, PR is twice of PQ (PR是对角,斜边). What is PR?
xy = 4(根号3)
2x = 根号(x^2 + y^2) x = 2 PR = 4
另:x * (根号3) * x = 4根号3 x = 2 PR = 4 (一个角是30度)
300. 圆内切一个长方形,一条边长2,另一条边长12,求圆半径。算出来根号下37。
144 + 4 = 148 所以圆直径是 2 根号37 所以。。。 |
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