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# Proving two vectors are coplanar and finding the Cartesian equation of the plane whic watch

1. Show that r = 3i+2j+k+t(-i+2j+k) and r=3i+9j+2k+t(2i+3j-k) are coplanar and finding the Cartesian equation of the plane which contains them.

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2. (Original post by SpanishTashman)
Show that r = 3i+2j+k+t(-i+2j+k) and r=3i+9j+2k+t(2i+3j-k) are coplanar and finding the Cartesian equation of the plane which contains them.

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3. crossing their direction vectors and dotting the answer with any of the 2 direction vectors should give you zero if coplanar
4. Okay I've crossed the direction vectors and got -5i+j-7k, how would I go about dotting that? As in which vectors represents a and n?

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5. (Original post by TeeEm)
crossing their direction vectors and dotting the answer with any of the 2 direction vectors should give you zero if coplanar
Okay I've crossed the direction vectors and got -5i+j-7k, how would I go about dotting that? As in which vectors represents a and n?

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6. (Original post by SpanishTashman)
Okay I've crossed the direction vectors and got -5i+j-7k, how would I go about dotting that? As in which vectors represents a and n?

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Ok

bit busy here

if the lines intersect then they are Coplanar since they are not parallel

So find intersection

the cross product of their direction then is the normal of the plane they define

use the intersection point and the normal to find plane
7. c4?
8. (Original post by coolgamer)
c4?
Nope FP3.

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9. (Original post by TeeEm)
Ok

bit busy here

if the lines intersect then they are Coplanar since they are not parallel

So find intersection

the cross product of their direction then is the normal of the plane they define

use the intersection point and the normal to find plane
Sorry to have been a pain, thanks for the useful help.

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10. (Original post by SpanishTashman)
Sorry to have been a pain, thanks for the useful help.

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no pain

Just doing my own work as well

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Updated: December 3, 2014
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