數學功課唔識做(直線的坐標幾何)

2007-08-26 12:53 am

已知四點 A(0,0) B( -2.x) C(2,4) 和 D(6,2)，且 AC垂直於BD。
求X的值?

回答 (3)

2007-08-26 1:03 am

slope of AC= 4/2=2

as AC垂直於BD,
slope of AC X slope of BD = -1
slope of BD = -1/2

(x-2)/(-2-6)= -1/2
2(x-2)=8
x=6

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2007-08-26 1:00 am

AC 的斜率M1 = (4-0)/(2-0) = 2
BC 的斜率M2 = (x-2)/(-2-6) = -(X-2)/8

因為AC垂直於BD

So,

M1 X M2 = -1

(x-2)/4 = 1

x = 6

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2007-08-26 12:58 am

Slope of AC * Slope of BD = -1
(4/2) *(( x-2)/(-2-6)) = -1
x=6

參考: myself

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