有數唔識做...@@"

oscar

一條中三既數...
關於Deductive Geometry...
(b)題唔識...
請高人指點...
(第一次唔識做自己level既數...)

[ Last edited by oscar on 2005-3-30 at 06:19 PM ]

小耀

Originally posted by oscar at 2005-3-30 06:16 PM:
一條中三既數...
關於Deductive Geometry...
(b)題唔識...
請高人指點...
(第一次唔識做自己level既數...)

[ Last edited by oscar on 2005-3-30 at 06:19 PM ]

∵BE平分咗∠ABC,∴∠ABE=∠CBE
∠ABE=∠BEC(錯角,AB//EC)
∴∠CBE=∠BEC
   DC=DC(公共邊)
BY(a) ∵BD=DE
         ∴∠BDC=∠DEC
         ∴△BDC≡△EDC(A.A.S.)
俾我紅咗果句嘢...總覺得:『好串』[E-Ton]

[ Last edited by 小耀 on 2005-3-30 at 07:32 PM ]

oscar

Originally posted by 小耀 at 2005-3-30 18:34:

∵BE平分咗∠ABC,∴∠ABC=∠CBE
∠ABE=∠BEC(錯角,AB//EC)
∴∠CBE=∠BEC
   DC=DC(公共邊)
BY(a) ∵BD=DE
         ∴BDC=DEC
         ∴△BDC≡△EDC

[ Last edited by 小耀 on 2005-3-30 a ...

你d steps又第1行已經錯...
∠ABC=∠CBE係錯...

艾

Originally posted by 小耀 at 2005-3-30 18:34:

∵BE平分咗∠ABC,∴∠ABC=∠CBE
∠ABE=∠BEC(錯角,AB//EC)
∴∠CBE=∠BEC
   DC=DC(公共邊)
BY(a) ∵BD=DE
         ∴BDC=DEC
         ∴△BDC≡△EDC
俾我紅咗果句嘢...總覺得:『好 ...

∵BE BISECTS ∠ABC
∴∠ABD=∠CBD
∵∠ABE=∠BEC (ALT.∠S AB//EC)
∴∠CBD=∠DEC=∠ABD

上半應是這樣.....

oscar

Originally posted by 颱風溫黛 at 2005-3-30 18:48:

∵BE BISECTS ∠ABC
∴∠ABD=∠CBD
∵∠ABE=∠BEC (ALT.∠S AB//EC)
∴∠CBD=∠DEC=∠ABD

上半應是這樣.....

我就係做黎做去都係S.S.A.

細薯

a)
since AB//EC and AB=EC.
ABCE is a parallelogram .    (forget the reason)

therefore BD=DE  (just remember bisect each other , forget the reason)

b)
angle BDA = angle BDC = angleEDC = 90 degrees (parallelogram ge property)

we now have

[quote]
BD = ED (from (a))
DC = DC (common)
angle BDC = angleEDC

therefore
triangle BDC & triangle EDC are congruent. (RHS)

[/quote]

sorry.........誤會左.....

[ Last edited by smallpotato226 on 2005-3-30 at 07:04 PM ]

oscar

請大家盡量不要利用Properties of Quadrilaterals的知識來solve此題...

小耀

Originally posted by oscar at 2005-3-30 06:39 PM:

你d steps又第1行已經錯...
∠ABC=∠CBE係錯...

係咩...
乜原來錯架卅▽卅〣
-----------------------------------------
係喎...應該係∠ABE=∠CBE
原來自己打錯咗個英文字母,唔怪得知硬係覺得自己冇錯= ="
改番上面果度咯...咁咪A.A.S.囉...
冇錯呀...

[ Last edited by 小耀 on 2005-3-30 at 07:33 PM ]

小耀

Originally posted by 颱風溫黛 at 2005-3-30 06:48 PM:

∵BE BISECTS ∠ABC
∴∠ABD=∠CBD
∵∠ABE=∠BEC (ALT.∠S AB//EC)
∴∠CBD=∠DEC=∠ABD

上半應是這樣.....

相信這樣的一個小錯誤,在考試時,只能得到1分= ="
不過,打字打錯姐...希望考試果時,唔好寫錯就好了[E-Swe]

細薯

已和oscar 諗到啦
isos triangle...XD