Re: [中學] 三角函數

[wayne2011 (今年十三號星期五)]

※ 引述《wayne2011 (今年十三號星期五)》之銘言：
: ※ 引述《Honor1984 (奈何上天造化弄人？)》之銘言：
: :    sin(b)
: : ------------
: : sin(a)sin(r)
: :     2△CDE         CA CD  CB CE
: : = ------------------------------
: :    2△CAD 2△CBE   CD CE
: : = (3/2) (11/6)
: : = 11/4
: 原式
: =cos(gamma+alpha)/[sin(gamma)*sin(alpha)]
: =cot(gamma)cot(alpha)-1                        連比例
: 6/5=BCsin(gamma)/CAsin(alpha+beta)...分定      BE:DE:DA = 6:3:2
: 6/5=BCsin(gamma)/CAcos(gamma)...正餘弦互換     2   1
: cot(gamma)=5BC/6CA,同理,cot(alpha)=9CA/2BC.         3  2
: =(15/4)-1=11/4...ans

參考"標準奧數教程(初三分冊)"

習題2.1的4th題

2*6/(2+3)(3+6)=sin(gamma)sin(alpha)/cos(gamma)cos(alpha)

cot(gamma)cot(alpha)=15/4...此題為證明





--
※ 發信站: 批踢踢實業坊(ptt.cc), 來自: 61.58.103.35
※ 文章網址: https://www.ptt.cc/bbs/Math/M.1508380698.A.38F.html
推 JI1         : how do you understand the origin?
推 JI1         : and how do you understand the number zero?
→ wayne2011   : i don't know~maybe still have a long time to go~
推 JI1         : how do you understand the beginning...?:)