lilreddots

PROBLEM SOLVED THANKS!

[ 本帖最後由 lilreddots 於 2011-7-7 07:00 PM 編輯 ]

夏娜醬大好

我不打算把我的頭轉90度去看題目...

lilreddots

sorry i changed it!

夏娜醬大好

6(i) Ratio of length = 1:2
     Ratio of area = 1:4
(ii)AE:BE = 1:2
     EF:BC = 1:2
     AD = EF
     Area of AEF = Area of ADE

25. BE = Ltan22.5
       = Ltan45/[1+sqrt(1+tam^2 45)]
       = L/(1+sqrt2)
    AB+BE = L(2+sqrt2)/(1+sqrt2) = Lsqrt2 = AC

27. interior angle of a 9-gon = (7/9)(180)
    2*[180-(7/9)(180)]+A = 180 (angle sum of triangle)

28. Find angle BAF and angle BAR first.
    You get angle FAR.
    Ans = 180-2*angle FAR.

lilreddots

2 NEW QUESTIONS DONT KNOW Q5(II) AND Q3(II) PLEASE HELP!!

夏娜醬大好

3(ii)
CK = BK = 10
HK/CK = BK/BC
HK = 10(10/15) = 20/3

HK/BC = AK/AC
4/9 = AK/(AK+10)
AK = 8

HK/BC = AH/AB
4/9 = AH/(AH+20/3)
AH = 16/3

5(ii)
ABC~XBA an dABC~XAC.

AB/BX = BC/AB
AB^2 = BX*BC

AC/CX = BC/AC
AC^2 = CX*BC

lilreddots

is there any other simpler method to calculate Q25???? THANKSS

夏娜醬大好

那麼我用這個:

lilreddots

THANK YOU SO MUCHH!