[已解決]F.2 數學

[box=#FFFFFF]1a) 解不等式 30y+20(8-y)[u]<[/u]195
b)小明想購買禮物A和禮物B共8份送朋友﹐ 其中禮物A 的售價是每份$30 ﹐ 而禮物B的售價是每份$20。 已知小明想用不多於$195而買得最多禮物A 。
(i) 根據a 小題的結果﹐ 問小明應購買A和B各多少份﹖﹖
(ii) 求小明購買禮物所花的金額。[/box]
[box=#FFFFFF]2a ) (i) 請切換完整版來瀏覽圖片和連結
(ii) 由(a)(i) 小題的結果﹐解聯立方程   [b][size=6]{[/size][/b]2(a+b)+3(a-b) =13
                                                     3(a+b)-(a-b)     = 3
(iii) 由 (a) (i) 小題的結果﹐或用其他方法﹐解聯立方程 請切換完整版來瀏覽圖片和連結[/box]

[box=#FFFFFF]3. In the figure , ABCDEFGH is a regular octagon and EFLJK is a pentagon. KJI is a straight line.
請切換完整版來瀏覽圖片和連結
(a) Find the interior angle of the regular pentagon and the interior angle of the regular octagon.
(b) Find <LFG
(c) Find <IJL and the reflex < JLF
(d) Find <HIJ in terms of x .
(e) Find the value of x .[/box]

[box=#FFFFFF]4. In the figure, ABCDEFG is a hextagon formed by intersecting a regular 10-sided polygon and a regular n-gon. < BAG and < AGF are the interior angles of the regular 10-sided polygon, while <BCD , <CDE and <DE F are the interior angles of the regular n-gon.
請切換完整版來瀏覽圖片和連結
(a) Find < BAG
(b) Express <BCD in terms of n .
If < ABC= < GFE =81。( 81度 ) , find n .[/box]

[color=Red]** < 姐係角[/color]

[color=Blue]28 號要交~~ thz ^^[/color]

[[i] 本帖最後由 cHoi_vy 於 2007-5-28 06:09 PM 編輯 [/i]]

30y+20(8-y)<195
30y+160-20y<195
10y<35
y<__

自己計-v-
其他打緊

(i) 根據a 小題的結果﹐ 問小明應購買A和B各多少份﹖﹖
let y be the number of 禮物A that have to buy
therefore
禮物A=____
禮物B=8-禮物A

自己計-v-

(ii) 求小明購買禮物所花的金額。
禮物A x 30+禮物B x 20
=___

自己計-v-

2ai) from2,
y=3x-3---------(3)
sub 3 into 1
.
.
y=___
sub y into (3)
x=___

自己計-v-

(ii) 由(a)(i) 小題的結果﹐解聯立方程
let(a+b)=x-------------(1)
(a-b)=y--------------(2)

再自己計
唔明再問


(iii) 由 (a) (i) 小題的結果
let1/m be x---------------(1)
1/n be y----------------(2)

如(ii)咁自己計
唔明再問

(a) Find the interior angle of the regular pentagon and the interior angle of the regular octagon
用(n-1)x180=_____黎計
唔好話比我知未學過條公式-v-

(b) Find <LFG
interior angle of the regular octagon - the interior angle of the regular pentagon=_____

(c) Find <IJL and the reflex < JLF
<IJL :
180-  the interior angle of the regular pentagon=______

reflex < JLF:
360-the interior angle of the regular pentagon=_____

(d) Find <HIJ in terms of x
=180-x

(e) Find the value of x .
(6-2)x180=<HIJ +reflex < JLF+<IJL +<LFG+2x(interior angle of the regular octagon)
x=_____

*自己加個degree sign上去
唔明再問

[[i] 本帖最後由 bobbycute 於 2007-5-26 06:04 PM 編輯 [/i]]

第3題 -3333-`;
E 好似計錯 -V- 小心D好

A)  LET X BE EACH INTERIOR < OF THE REGULAR OCTAGON
  6X = [10-2] X 180" ( <SUM OF POLYGON )
       = 1440"
  X  = 240 "

B)  LET Y BE EACH INTERIOR < OF THE PENTAGON
5Y = [5-2] X 180"
       = 540"
Y   = 108"

C)   < LFE + < LFG = 240"  
  < LFG               = 240" - 108"
                            = 132"

D)  X + < HIJ = 240"
      
E)    < KJL = <HIJ = 108"  ( corr.< AH // LJ )
        X + <HIJ = 240"
       X + 108" = 240"
         X           = 132"

[quote]原帖由 [i]bobbycute[/i] 於 26/5/2007 18:03 發表
(a) Find the interior angle of the regular pentagon and the interior angle of the regular octagon
用(n-1)x180=_____黎計
唔好話比我知未學過條公式-v-

(b) Find <LFG
interior angle of the regu ...
(
e) Find the value of x .
([color=Red]6[/color]-2)x180=<HIJ +reflex < JLF+<IJL +<LFG+2x(interior angle of the regular octagon)
x=_____
[/quote]
點解係6-2 ??

[quote]原帖由 [i]kate`;}[/i] 於 2007-5-27 04:33 PM 發表

點解係6-2 ?? [/quote]
(n-2)x180
個條式黎架

做咩大家咁叻唔做第四題:em24:
a) (10-2)x180 / 10 = 144
b) (n-2)x180/n

81*2 + 144*2 + (n-2)x180/n * 2 = (6-2)*180
n = 8