1. 若4個蘋果的成本與3個蘋果的售價相同,找售10個蘋果的盈利百分率.
ans. 33.3%
2. 在triangle ABC中,則1+cos(B)cos(-A-C)=
ans. sin^2 B
3. sin^2 2 + sin^2 4 + sin^2 6 +......+ sin^2 86 + sin^2 88=
ans. 22
4. (2-5cos 2 A)^2 + 1 的極小值為
ans. 1
i would like to have the solution ..thz^^
maths F.5問題
2010-04-11 7:26 pm
回答 (3)
2010-04-11 8:30 pm
✔ 最佳答案
圖片參考：http://i.imagehost.org/0088/ScreenHunter_03_Apr_11_12_28.gif
http://i.imagehost.org/0088/ScreenHunter_03_Apr_11_12_28.gif
2010-04-12 07:45:38 補充：
當cos2A=2/5時,
可得極小值=[2-5(2/5)]²+1
=1
2010-04-11 9:36 pm
SOMUCH你第一題錯左...應該係4C=3P
2010-04-11 8:20 pm
3. sin^2 2 + sin^2 4 + sin^2 6 +......+ sin^2 86 + sin^2 88
=sum(k=1,22) ((sin(2k))^2+(sin(90-2k))^2
=sum(k=1,22) ((sin(2k))^2+(cos(2k))^2
=sum(k=1,22) 1
=22//
4. -1<cos2A<1
=>-5<-5cos2A<5
=>-3<2-5cos2A<7
=>9<(2-5cos2A)^2<49
=>10<(2-5cos 2 A)^2 + 1<50
minimum = 10//
1+cos(B)cos(-A-C)
=1+cosBcos(B-180)
=1-cosBcosB
=sin^2B//
1. let cost = C and price = P
then 3C=4P => P=3/4C
profit percentage
=(P-C)/C x100%
=(3/4C-C)/C x100%
=25%//
=sum(k=1,22) ((sin(2k))^2+(sin(90-2k))^2
=sum(k=1,22) ((sin(2k))^2+(cos(2k))^2
=sum(k=1,22) 1
=22//
4. -1<cos2A<1
=>-5<-5cos2A<5
=>-3<2-5cos2A<7
=>9<(2-5cos2A)^2<49
=>10<(2-5cos 2 A)^2 + 1<50
minimum = 10//
1+cos(B)cos(-A-C)
=1+cosBcos(B-180)
=1-cosBcosB
=sin^2B//
1. let cost = C and price = P
then 3C=4P => P=3/4C
profit percentage
=(P-C)/C x100%
=(3/4C-C)/C x100%
=25%//
收錄日期: 2021-04-22 00:47:38
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100411000051KK00446