在锐角△ABC中,试求sinA+sinB+sinC的取值范围是一道高二数学竞赛试题,麻烦看一看,会的教一教

在锐角△ABC中,试求sinA+sinB+sinC的取值范围是一道高二数学竞赛试题,麻烦看一看,会的教一教
在锐角△ABC中,试求sinA+sinB+sinC的取值范围
是一道高二数学竞赛试题,麻烦看一看,会的教一教

在锐角△ABC中,试求sinA+sinB+sinC的取值范围是一道高二数学竞赛试题,麻烦看一看,会的教一教
t=sinA+sinB+sin(A+B)=sinA+sinB+sinAcosB+cosAsinB=sinA(1+cosB)+sinB(1+cosA)=sinA*2cos^2 B/2 +sinB*2cos^2 A/2 =4cosA/2 cosB/2(sinA/2cosB/2+sinB/2cosA/2)=4cosA/2cosB/2sin(A+B)/2=4cosA/2cosB/2cosC/2
算不下去了,猜吧.
t对A求导,求A为某值,t取极值.由于A、B等效可替换,对B求导,求极值仍然是与A值相同,所以,A=B同时取某值时,取极值,又A,B,C等效.所以,A=B=C时取极值,即为（3√3）/2.另一范围必在边界条件处确定,锐角三角形,a²+b²>c²,直角三角形a²+b²=c²,钝角三角形,a²+b²c时b->0,最小为2
所以,2

The picture shows the scene of the accident Yi Tang deter
6 月 27 日 around 19:00,cartier watches, Xishan District, Wuxi, Zhang Yang Road and Incubation Road T-junction, a sheep from the tip of Wu...

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The picture shows the scene of the accident Yi Tang deter
6 月 27 日 around 19:00,cartier watches, Xishan District, Wuxi, Zhang Yang Road and Incubation Road T-junction, a sheep from the tip of Wuxi Changan bound to large trucks to avoid driving across the Unfortunately, to the car overturned, killing two dead 8 injured in the tragedy.
truck roll stuffed tragedy

27 at 7:00 pm or so, Mr. Wang and his four workers are usual in Zhang Yang Road, near the construction site work. Sudden \Mr. Wang went to Zhang Yang Road and Incubation Road T-junction,omega watches, saw a 9-meter-long roll in the whole truck, the car has no glass-li, also under pressure inside a man. \down. Camphor is a lot of pressure following a person, some people are arm pressure, and some people is to suppress the leg,bvlgari watches, these people are given pain Ku groaning under a tree. Even more frightening is that the sidewalk in the road also lies a man, man's head hit the pavement on the floor tiles, broke a big hole, blood is bubbling out from the wound in the flow.
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passers-by have a helping hand

happened, many good people have come to crossing the salvage facilities. There are many people injured crossing the road after the driver saw the car parked in the side, and then joined the ranks of salvage assistance. Subsequently, emergency salvage center in Wuxi City, three salvage cars rushed to the trouble protecting the scene, the doctor will be the scene of the wounded carried to a salvage vehicle care, Ji were sent to nearby hospitals. 20:00 the same day, reporters rushed to the scene, saw the road accident still littered with a lot of camphor trees. A crowd gathered and told reporters that the car accident contained a total of 14 individuals, 4 were in the cab, there are 10 people with standing trees inside.
yesterday, in Wuxi Xishan Hospital, the reporter saw a wounded Chow, Chow's left foot was pressed trees below the swollen mouth are clear of blood. \\\six wounded from the scene of the accident rushed to hospital for treatment, of which 5 per person for the injury,ugg australia, currently has no life crisis Yan, 1 101 have been transferred to the hospital. then it went to press about 101 hospitals, the medical staff told reporters sent to the House of the injured is head injury, now has no life crisis Yan. Afterward, the reporter learned that there are two injured were rushed to Wuxi Second People's Hospital, currently there is no life crisis Yan.

a deceased son test this year, a large divider

in the accident, two were killed. A source said the two dead people are in Guizhou, a talent more than 20 years old,uggs outlet, another 40 years old. an understanding of the deceased revealed that villagers in Guizhou, 40-year-old man named Liu, Ryu and his wife have a son just this year, great curb examination, the son of Zan order to curb the cost of a big, Ryu in the last year and Wuxi wife working together. and another incident in the 20-year-old young man has not married, the young man's family home in Guizhou also have only one uncle working in Wuxi. Now the young family that their son after the accident, grief stricken, was rushed to the way in Wuxi.

It is understood that Changan traffic police squadron had been investigating the matter. An informed source revealed: the truck drivers and company owners have been Changan Police Control .

Express correspondent Yi Tang

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