题目

先在此谢过各路好汉了!
1---In triangle ABC,AB=AC=2,whch of the following culd be the area of triangle ABC?Indicate all possible areas.A) 0.5 B) 1.0 C) 1.5 D)2.0 E) 2.5 F)3.0
2---Each integer from 1 to 50 whose units digit is a 3 is written on a slip of paper and placed in a box.If two slips of paper are drawn at random,what is the probability that both numbers are prime?(答案是几分之几)
3---A jar contains 20 marbles:4 red,6 white and 10 blue.If you remove one at a time,randomly,what is the minimum number that must be removed to be certain tat you have at least 2 marbles of each colors?
A) 6 B) 10 C) 12 D) 16 E) 18
默默地自己鄙视一下自己的烂数学.想知道解题过程.

提问时间：2020-11-05

答案

1.由于三角形面积S=absinC/2;而本题的a=b=2,故S=2xsinC.又因为0