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匿名 發問於 科學及數學數學 · 1 十年前

FORM 2 MATHS [theory]


三角形 既內角 既總和 一定係180° ,

呢個theory係----> ∠sum of △

我想問四邊形 既內角 既sum 係咪一定係360° ???

如果我想解釋點解係咁, 應該用邊條theory?

我就響度諗, 係咪「 ∠sum of polygon 」

不過我check返, 呢條theory係指 (n-2)÷180 呢d野...根本套用唔到~


我係用New Trend Mathematic S2B (呢課係Chapter 9)既書~

如果你有呢本書, 可以既睇下~

2 個解答

  • 1 十年前

    對於polygon, 唔同人(或者書)會有唔同既定義,

    in Wikipedia 就有兩個唔同既定義:


    In geometry a polygon (IPA: [ˈpɒliɡən], from the Classical Greek πολυγον, meaning literally "many-knee" or "many-angle") is a plane figure that is bounded by a closed path or circuit, composed of a finite number of sequential line segments. The straight line segments that make up the boundary of the polygon are called its edges or sides and the points where the edges meet are the polygon's vertices or corners. The interior of the polygon is its body.


    Polygons are named and classified according to the number of sides, combining a Greek-derived numerical prefix with the suffix -gon, e.g. pentagon, dodecagon. The triangle, quadrilateral, and nonagon are exceptions. For large numbers, mathematicians usually write the numeral itself, e.g. 17-gon. A variable can even be used, usually n-gon. This is useful if the number of sides is used in a formula.

    如果根據(1), 四邊形係多邊形既一種, 所以係可以用∠sum of polygon

    而(n-2)÷180 條式係完全正確的

    ∠sum=(4-2)÷180=360 (∠sum of polygon)

    [n 係代表有幾多條邊, 即係4]

    原因就如原因就如de_familiar_stranger 講咁你可以cut 開個四邊形做兩個三角形


    我地多數就會好似leuk115 咁

    用(∠ sum of quad.)

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  • 1 十年前


    (∠ sum of quad.)

    2007-02-23 13:38:02 補充:

    條theory係 (n-2)x180

    2007-02-23 14:09:06 補充:

    我唔明why ∠sum=(4-2)÷180=360 (∠sum of polygon)

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