Vector

2012-10-18 9:15 am
A vector equation for a given straight line is r = (i + 3j) + lambda (-i - j)

Construct a vector equation for the line that does go through the point (1,2), and is perpendicular to r.

and

Determine the point of intersection of the two lines

回答 (1)

2012-10-18 6:23 pm
✔ 最佳答案
Direction vector of the given line is -i - j, thus we can choose i - j as the direction vector of the required line.

Hence the vector equation is:

(i + 2j) + p(i - j) where p is a real variable.

In parametric form, the given line is x = 1 - λ and y = 3 - λ

The required line is x = 1 + p and y = 2 - p

So we haev:

1 - λ = 1 + p and 3 - λ = 2 - p

Solving we have p = -1/2 and λ = 1/2

So the point of intersection is at (1/2. 5/2)
參考: 原創答案


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