Raymond 發問於 科學及數學數學 · 1 十年前

F2 math deductive geometry

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help me plx.. 20points!~~

3 個解答

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  • 最愛解答

    DFE=a+b(ext ange of triangle)

    DFE+c=135(ext angle of triangle)

    a+b+c=135

    __________________

    2010-12-14 20:52:51 補充:

    d=CFG(corr. angle ,AG//DE)

    CBF+b=180(adj. angles on a st. line)

    CBF=180-b

    c+180-b=d(ext angle of triangle)

    -b-d=-180-c

    b+d=180+c

  • 蛙人
    Lv 6
    1 十年前

    AngleAFD = d (alt. angles, AF//DE)

    Hence angleAFC = 180 - d (adj. angles on st. line)

    Thus 180 - d + c = b (ext. angle of triangle)

    b + d = 180 + c

  • 1 十年前

    I only know the upper question.

    a+b= └DFE (ext.└ of triangle)

    c+└DFE =135 (ext.└ of triangle)

    a+b+c=135

    I hope it can help u!

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