已知θ是三角形的一个内角，且sinθ、cosθ是关于x的方程2x2+px-1=0_爱下问搜题

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问题选择题

已知θ是三角形的一个内角，且sinθ、cosθ是关于x的方程2x²+px-1=0的两根，则θ等于（　　）

A．

π

4

B．

π

3

C．

3π

4

D．

5π

6

答案

∵sinθ、cosθ是关于x的方程2x²+px-1=0的两根，

∴

sinθ+cosθ=-

p

2

①

sinθcosθ=-

1

2

②

∴①²-②×2，可得

p2

4

+1=1

∴p=0

∴sinθ+cosθ=0

∵θ是三角形的一个内角，

∴θ=

3π

4

故选C．

阅读理解

Name	The Palace Museum	British Museum	New York Museum
Country	China	The UK	The USA
Address	Chang’an Street	New Oxford Street, London	Chestnut Street, New York
Feature	The largest ancient palace buildings with many kinds of collections in China	One of the largest museums with collections of any time and any area in the world	America’s largest museum on American history
Ticket	￥60 ( Spring＆ Summer) ￥40 (Autumn ＆Winter)	Free	Monday free

小题1:As one of the largest museums in the world, British museum is in _______ .

小题2:New York Museum is America’s largest museum on American__________.

C．collections

小题3:The Palace Museum. Which is in the center of Beijing, is also called “Forbidden City(紫禁城)” in China. It lies in __________.

A．Chang’an Street

B．New Oxford Street

D．Chestnut Street

小题4:According to the form, if you want to see ancient Chinese collections, you can visit ____ at most.

B．two museums

C．three museums

D．fore museums

小题5:Which of the following is TRUE according to the information above?

A．Each ticket for the Palace Museum costs the same in the whole year.

B．You don’t have to pay for tickets if you visit New York Museum on Monday.

C．British Museum lies in Chestnut street, London.

D．New York Museum is the largest in the world.

问答题简答题

1926年7月9日，叶开鑫在长沙汽车站，准备抢劫全部汽车，而保卫长沙汽车站的工人是谁呢？