F.4 maths

2010-06-27 4:05 am
Consider two straight ines L1 : y=√3 x
and L2: 2√3 x-2y+5=0

a. Show that L1 parallel to L2.

b. find inclination and x-int. of L2

c. Hence, find the distance between L1 and L2.

I have done the steps a and b ,
PLS help me to do c.
thx.

Diagram: http://www.flickr.com/photos/51470019@N07/4734884461/

回答 (1)

2010-06-27 4:51 am
✔ 最佳答案
a.
L1: y = (√3)x
L2: 2(√3)x - 2y + 5 = 0

Slope of L1 = √3
Slope of L2 = -(2√3)/(-2) = √3

Since L1 and L2 have equal slopes, L1 // L2.


b.
L2: 2(√3)x - 2y + 5 = 0
When y = 0:
2(√3)x - 2(0) + 5 = 0
x = -5/(2√3) = -5(√3)/6
Hence, x-intercept of L2 = -5(√3)/6

Slope of L2 = tanθ = √3
Inclination of L2, θ = 60°


c.
L1: (√3)x - y = 0
(-5(√3)/6, 0) lies on L2.

Distance between L1 and L2
= Distance between L1 and (-5(√3)/6, 0)
= |(√3)( -5(√3)/6) - 0| / √[(√3)² + 1²]
= (5/2) / 2
= 5/4
(or 1.25)
參考: adam


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