maths

a. 設M為(x , y)

x = (16 - 8) / 2 = 4

y = (8 - 4) / 2 = 2

所以，M(4 , 2)

AB的斜率 = (-4 - 8) / [16 – (-8)] = -1 / 2

所以，1的斜率為2

1的方程:

y – 2 = 2(x - 4)

y – 2 = 2x – 8

2x – y – 6 = 0

b. 代y = 0 入1的方程

2x – 0 – 6 = 0

x = 3

所以，P(3 , 0)

因此，BP

= √[(16 - 3)2 + (-4 - 0)2]

= √185

c. 設N(a , b)

a = (3 - 8) / 2 = -5 / 2

b = 8 / 2 = 4

所以，N(-5 / 2 , 4)

MN

= √{[4 – (-5 / 2)]2 + (2 - 4)2}

= √185 / 4