A maths!?!? o_O|||

dolphin_ice

究竟係創意，定係惡搞呢？[E-TeH]

小耀

惡搞= ="
邊可以咁樣約架[E-Swe]
p.s.:好慘...考mock果時,2cos5x=0...我將佢變o左做cos5x=1/2= ="
      就係E題...今次又可能唔合格喇[E-Ah]

SusanCrystal

我試過兩邊直接刪左個cos...
但係都好似solve到喎:

cos(a+1.5)=cos(2.5-a)
a+1.5=2.5-a
2a=1
a=0.5

阿sir照tick=.=

WildFlowers

Originally posted by SusanCrystal at 2005-3-20 10:26 PM:
我試過兩邊直接刪左個cos...
但係都好似solve到喎:

cos(a+1.5)=cos(2.5-a)
a+1.5=2.5-a
2a=1
a=0.5

阿sir照tick=.=

你笨喔…為啥不對…
當a+1.5=2.5-a時，兩邊同時cos掉都相等的嘛…

oscar

Originally posted by WildFlowers at 2005-3-20 23:33:

你笨喔…為啥不對…
當a+1.5=2.5-a時，兩邊同時cos掉都相等的嘛…

你仲笨呀！
你有冇學過cos(360*n+x)=cos x (n for any integer)嫁~

小耀

Originally posted by oscar at 2005-3-21 12:57 AM:

你仲笨呀！
你有冇學過cos(360*n+x)=cos x (n for any integer)嫁~

To oscar:唔好咁樣話人...唔係個個都讀過A.Math架...
To#4:oscar講果D係三角學的通解= ="你問問讀A.Math的朋友就知道是什麼來了...
正確的解法(應該無錯的^^):
cos(a+1.5)=cos(2.5-a)
a+1.5=360度n+/-(2.5-a)
a+1.5=360度n+2.5-a or a+1.5=360度n-2.5+a
2a=360度n+2.5-1.5   or a-a=360度n-4
  a=180度n+1/2        or       無解
∴a=180度n-1/2,其中n為一常數。
(天:點解考試果時,又唔見你咁醒\ . /)
(我:我都唔知點解╭(╯~╰)╮今次就係一題通解,又有可能唔合格喇＞＜)

[ Last edited by 小耀 on 2005-3-21 at 10:35 AM ]

Harpuia

Originally posted by 紅唇娃 at 2005/3/20 19:09:
究竟係創意，定係惡搞呢？[E-TeH]

POST過N年了..............

小耀

Originally posted by BBQ at 2005-3-21 12:54 PM:

POST過N年了..............

是嗎@@？在看此post前,me未見過...
不過,E題數都做唔倒的(在我這個階段...)
因為都唔知果舊o野=咩...就算知...都淨係搵到X=咩...果咩度仲有個未知數n[E-Swe]

Harpuia

Originally posted by 小耀 at 2005/3/21 14:21:

是嗎@@？在看此post前,me未見過...

之前發果陣你未

小耀

[quote]Originally posted by BBQ at 2005-3-21 05:59 PM:

之前發果陣你未