equation of st.line............

q1

equation of AB:
(y-5)/(x-2) =(5-3)/(2-6)
(y-5)/(x-2) = 2/(-4)
-4y + 20 = 2x - 4
2x + 4y - 24 = 0
x + 2y - 12 = 0

SLOPE OF EQUATION AB IS -1 / 2 ( SLOPE = -A/B)

THEREFORE , THE REQUIRED SLOPE OF EQUATION * -1/2 =-1

THE REQUIRED SLOPE OF EQUATION = 2

Y-5 / X -2 = 2
Y-5 = 2X -4
2X-Y+1 =0


q2a , 因為 two stright lines L2 and L3 intersecting at (-2,5).

SLOPE OF L 1 = 2

required equalion of L2 : y-5 / x+2 = 2
y-5 = 2x+4
2x-y+9 = 0


Q2B SLOPE OF L 1 = 2

SLOPE OF L3 * 2 = -1

SLOPE OF L3 = -1/2

EQUATION OF L3

y-5 / x+2 = -1/2
2y-10 = -x -2
x + 2y - 8 = 0


教你小小tips ..
你計到一條 equation 之後可以代返落去試下係咪 = 0
如果唔係即係你計錯左啦 -3-
add oil !!

2007-04-01 18:53:12 補充：
我本身用 SPACE BAR 隔到岩岩好.. " = " 係一行過而家好難睇..SORRY /.\