Equations for a Line Passing Through Two Given Points in 3D Space

In summary: And then you can use that vector, PQ, as the direction vector in your parametric equation for the line.
  • #1
somebodyelse5
37
0

Homework Statement



Find the vector and parametric equations for the line through the point P(-3, 3, -5) and the point Q(-7, 4, -1).

Homework Equations



N/A

The Attempt at a Solution



r= <__,__,-5>+t<__,__,4> The -5 and 4 are given.

Heres what I have so far. r=<-3,3-5>+t<__,__,__>

I am totally lost on how to find those other two points and the equations.
 
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  • #2
somebodyelse5 said:

Homework Statement



Find the vector and parametric equations for the line through the point P(-3, 3, -5) and the point Q(-7, 4, -1).

Homework Equations



N/A

The Attempt at a Solution



r= <__,__,-5>+t<__,__,4> The -5 and 4 are given.

Heres what I have so far. r=<-3,3-5>+t<__,__,__>

I am totally lost on how to find those other two points and the equations.
Think of it in terms of adding vectors - one vector from the origin to a given point on the line, and another vector from the given point on the line to an arbitrary point on the line.

Your vector equation of the line will be r = OP + t*PQ

What you're missing is a vector that gives the direction of the line.
 
  • #3
Mark44 said:
Think of it in terms of adding vectors - one vector from the origin to a given point on the line, and another vector from the given point on the line to an arbitrary point on the line.

Your vector equation of the line will be r = OP + t*PQ

What you're missing is a vector that gives the direction of the line.

Ok, Is the value of 4, which is givin in the problem as the z value in the second vector, a clue at all?

I tried multiplying P and Q and then dropping them all down so that they agree with the z=4 value and that didnt work. Its not that simple is it? PQ doesn't mean I can just multiply P and Q together does it?
 
  • #4
How do you find the vector from P to Q? You don't multiply - that makes no sense at all.
 
  • #5
Mark44 said:
How do you find the vector from P to Q? You don't multiply - that makes no sense at all.

Oh ok, I am still thinking in basic algebra. Not much time spent on vectors yet.

So I would to Q-P to get PQ.
 
  • #6
Yes.
 

Related to Equations for a Line Passing Through Two Given Points in 3D Space

1. What is the difference between a line and a plane in calculus 2?

A line is a one-dimensional geometric figure that extends infinitely in both directions. In calculus 2, it is often represented by an equation in the form of y=mx+b, where m is the slope and b is the y-intercept. A plane, on the other hand, is a two-dimensional figure that extends infinitely in all directions. In calculus 2, it is represented by an equation in the form of Ax + By + Cz = D, where A, B, and C are the coefficients and D is the constant term.

2. How do you find the equation of a line in calculus 2?

To find the equation of a line in calculus 2, you need to know the slope and a point on the line. You can use the point-slope form of a line, y-y1 = m(x-x1), where (x1,y1) is the given point and m is the slope. Alternatively, you can use the two-point form of a line, (y-y1)/(x-x1) = (y2-y1)/(x2-x1), where (x1,y1) and (x2,y2) are two given points on the line.

3. What is the normal vector of a plane in calculus 2?

The normal vector of a plane in calculus 2 is a vector that is perpendicular to the plane. It is represented by the coefficients of the plane equation, (A,B,C). The normal vector is important in determining the orientation and angles of the plane in relation to other geometric figures.

4. How do you find the intersection of a line and a plane in calculus 2?

To find the intersection of a line and a plane in calculus 2, you need to solve for the coordinates of the point where they intersect. This can be done by setting the equations of the line and the plane equal to each other and solving for the variables.

5. What is a vector equation in calculus 2?

A vector equation in calculus 2 is an equation that represents a line or plane using vectors. It is written in the form of r = r0 + tv, where r is the position vector, r0 is a known point on the line or plane, t is a scalar, and v is the direction vector. This form is useful for calculating distances, angles, and projections in 3-dimensional space.

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