每日一问。。数学题。

qiongyue0312

1.In the triangle above, is x > 90?(图是一个三角形，a,b,c都是边，c所对的角是x)

(1)    a² + b² < 15

(2)     c > 4

2.Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day.  If
                        r percent of the store’s revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expresses r in terms of p?

 

A.     100p / (125 – p)

B.     150p / (250 – p)

C.     300p / (375 – p)

D.     400p / (500 – p)

E.      500p / (625 – p)

答案1C2D

sqsouare

1、首先可以确定单独一或者单独二都无法回答问题，联立一跟二，假设为直角三角形，且a^2+b^2=15,则c应该为根号15，而实际上根据条件2，c>4，则其所对的角大于90°。

2、设总共卖了X份报纸，给据已知条件列出方程，1*p%*X/[1*p%*X+1.25*(1-p%)*X]=r%,约去X并化简求得D答案。

qiongyue0312

谢谢sqsouare~~~原谅我每次都问这么弱智的题~~