急! CE Maths(Section A)(應該唔係pp)－貨運百科

標題:

急! CE Maths(Section A)(應該唔係pp)

發問:

此文章來自奇摩知識+如有不便請留言告知

有三題,1. The number of sides and the number of vertices of a polyhedron are 15 and 10 respectively. Find the number of faces. (3marks)2. 請看圖可能有d 唔清楚, graph= y = 4^x3-6^x2-9x+3[IMG]http://i104.photobucket.com/albums/m167/indifferentwind/q2.jpg[/IMG]3.... 顯示更多有三題, 1. The number of sides and the number of vertices of a polyhedron are 15 and 10 respectively. Find the number of faces. (3marks) 2. 請看圖可能有d 唔清楚, graph= y = 4^x3-6^x2-9x+3 [IMG]http://i104.photobucket.com/albums/m167/indifferentwind/q2.jpg[/IMG] 3. 都係看圖 [IMG]http://i104.photobucket.com/albums/m167/indifferentwind/q3.jpg[/IMG] 要full step, thx~ 更新: 回煩惱即是菩提 : 這是老師就CE課程給我們做的一些練習, 程度是Section A的, 而且應該是他自行出, 或從其他練習題抽出來的, 故應該不是 past paper 的題目。我都有東西想問一下, 請問 Euler formula 應該是中一至中五裡哪一年學的?? 好像沒多印象呢... Orz 更新 2: In Q.3 (a), why OX = 24cm?? sorry about that...

最佳解答:

Q1. By Euler formula: V-E+F=2, thus 10 - 15 +F=2 =>F= 7 Q2. 8x^3- 12x^2 - 18x - 5=0 => 4x^3 - 6x^2 - 9x + 3 = 11/ 2 By the given graph, find the x values such that y=f(x)= 11/2 Thus, I guess x= - 0.5 , -0.5 and 2.5 and they are exact roots. Q3. a). In △ODX: OX=24, OD=12 , thus ∠DOX= 60 degrees, so is ∠COY Therefore, ∠XOY= 60 degrees b). Arc length of XMY= 2π*24 * 60/360 = 8π Area of OXMY=π*24^2 * 60/360= 96π c) Circumference = arc length of XMY= 8π=>radius of the cone r = 4 Height of the cone h = √(24^2 - 4^2)= 4 √35 Volume = (1/3) π*r^2*h= 4√35π / 3 2009-01-12 01:55:54 補充： Correct: Q3: c) V= (1/3)π*r^2*h= 16√35π / 3 2009-01-12 02:08:09 補充：請解釋一下:CE Maths(Section A)(應該唔係pp) 的意思,OK!? 2009-01-12 02:42:49 補充：應屬立體圖形部分,不知中幾吔! (中三嗎?) 2009-01-12 02:44:36 補充： From fig5(a), OX=OM=AD= 24

其他解答:

V-E+F=2 係中`一就學咖啦|||||剛才上網看過數學科的syllabus，真的沒有V-E+F=2，但我好像在某些教科書中看見過，也許有些中學有教也說不定。|||||IT's university maths|||||菩提兄...... 香港中學並沒有學過Euler Formula呢...... 非常糟糕的事實......