F2 Mathe(新增一題) [複製鏈接]

最好附步驟
謝！

draw a line of AF.
then angle BAF and angle EFA =90 degree
angle sum of ABCDEF =
180*(6-2)=720 degree

x=720-90-90-143-267-26
=104 degree

B

First, produce two lines (G , H ) passing through C and D respectively which are parallel to AB and FE

Suppose GC // HD // AB // FE

angle HDE = 180-26 (interior angles, FE//HD)
angle HDE =  154

angle HDC = 267-154
angle HDC = 113

angle GCD = 180-113(interior angles, GC//HD)
angle GCD = 67

angle BCG = 180-143(interior angles, GC//AB)
angle BCG = 37

therefore, x = 67+37
                     = 104

哦，先謝2位
一會再睇，

還有一題......

首先:
x(3z)=y(2z-5)+3z
    3zx=2zy-5y+3z
   3zx-2zy-3z=-5y
    z(3x-2y-3)=-5y
    z=-5y除(3x-2y-3)
    z=5y除(將負號插去變成)(-3x+2y+3)
所以z=5y除(2y-3x+3)
答案是C
希望幫到你!