1.
a[n] = S[n]-S[n-1] = 1/2 (√S[n]+√S[n-1])
==> √S[n] - √S[n-1] = 1/2
==> √S[10] - √S[4] = 1/2 * 6 = 3,√S[4]=√4=2
==> √S[10] = 5,
==> S[10] = 25
2.
tanB = sinB/cosB = 1/3
==> tan(A+B) = (1/2+1/3)/(1-1/2*1/3) = 1
==> tanC = -tan(A+B) = -1
sinA=√5/5,sinB=√10/10,sinC=√2/2
==> sinC>sinA>sinB ==> c>a>b
==> b/c = sinB/sinC = √5/5
==> b=√5/5
1.已知數(shù)列{an}的前四項(xiàng)和等于4,設(shè)前n項(xiàng)和為Sn,且n≥2時(shí),an=1/2（根號(hào)Sn+根號(hào)Sn-1),求S10
1.已知數(shù)列{an}的前四項(xiàng)和等于4,設(shè)前n項(xiàng)和為Sn,且n≥2時(shí),an=1/2（根號(hào)Sn+根號(hào)Sn-1),求S10
2.在△ABC中,角A.B.C所對(duì)的邊分別是a.b.c,tanA=1/2,cosB=3倍根號(hào)10/10,
①求tanC的值；②若△ABC的最長(zhǎng)邊是1,求最短邊的長(zhǎng).
2.在△ABC中,角A.B.C所對(duì)的邊分別是a.b.c,tanA=1/2,cosB=3倍根號(hào)10/10,
①求tanC的值；②若△ABC的最長(zhǎng)邊是1,求最短邊的長(zhǎng).
數(shù)學(xué)人氣：226 ℃時(shí)間：2020-05-19 00:55:19
優(yōu)質(zhì)解答
我來(lái)回答
類似推薦
- 1.已知數(shù)列{an}的前四項(xiàng)和等于4,設(shè)前n項(xiàng)和為Sn,且n≥2時(shí),an=1/2（根號(hào)Sn+根號(hào)Sn-1),求S10
- 數(shù)列｛an｝的項(xiàng)前4項(xiàng)和等于4 且n>=2時(shí) an=1/2*（根號(hào)Sn+根號(hào)S（n-1）,）則S10=————
- 數(shù)列an的前4項(xiàng)和等于4,且當(dāng)n≧2時(shí),an=1/2（根號(hào)下Sn+根號(hào)下S(n-1)）,則S10等于多少
- 已知正數(shù)數(shù)列{an}的前n項(xiàng)和為Sn,且對(duì)任意的正整數(shù)n滿足 2倍的根號(hào)下Sn等于an+1,求數(shù)列{an}的通項(xiàng)公式?
- 已知數(shù)列｛An｝的前n項(xiàng)和為Sn,且S4等于4,且n大于等于2時(shí),滿足An等于（根號(hào)Sn+根號(hào)S(n+1))/2
- 大小行星繞地球公轉(zhuǎn)的共同特點(diǎn)是什么
- 2sin45度+|負(fù)根號(hào)2|-根號(hào)8+（3分之一）負(fù)一次方
- 長(zhǎng)100米寬100米是多少平米和幾畝地 長(zhǎng)50米寬50米是多少平米和幾畝地
- 急求一篇英語(yǔ)對(duì)話兩人的關(guān)于How do you plan your university years?
- "疑是銀河落九天"的"九天"是什么意思?
- 怎么證明(m+n)^2/2+(m+n)/4>mn^(1/2)+nm^(1/2),已知m>0,n>0
- 這段話是否有語(yǔ)法錯(cuò)誤(英語(yǔ))
猜你喜歡
- 1急 若(2X(的三次方 - (KX)的平方+3被2X+1除后余2,求K的值
- 2I like some bread and milk for breakfast.在這個(gè)句子
- 3連詞成句：a,tomorrow,I,have,test,late,I,stay,can't,out,because
- 4是不是只有熱的物體才能發(fā)光?
- 5根號(hào)Y-1與根號(hào)1-2X互為相反數(shù),求根號(hào)Y除以X
- 6如圖,已知B為線段AC上的一點(diǎn),M是線段AB的中點(diǎn),N為線段AC的中點(diǎn),P為NA的中點(diǎn),Q為MA的中點(diǎn),求MN:PQ的值.
- 7設(shè)A*是三階方陣A的伴隨矩陣,若|A|=2,則秩R(A*)=?
- 8英語(yǔ)單詞大全
- 9宮本武藏的藏的發(fā)音是zang還是cang?
- 10運(yùn)輸隊(duì)要運(yùn)2000件玻璃器皿，按合同規(guī)定，完好無(wú)損運(yùn)到的每件付運(yùn)輸費(fèi)1.2元，如有損壞，每件沒(méi)有運(yùn)輸費(fèi)外，還要賠償6.7元，最后運(yùn)輸隊(duì)得到2005元，運(yùn)輸中損壞了多少件玻璃器皿？
- 11Newspapers and magazines have special interest in the private lives of famous people.
- 1212生肖中,善良的動(dòng)物有