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Line of Intersection of 2 Planes:


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Find the line of intersection, L, of planes

P1: 5x – 3y – 2z = 7, and P2: 2x – y + 3z = 4.

The line of intersection, L, lies in both planes, and hence is perpendicular to the normal vectors of both planes. The cross product, n1 ´ n2, is also perpendicular to n1 and n2, so it can be used as a reference vector in the direction of the line.

From the equations, we can determine the normal vectors:

n1 = 5i – 3j – 2k, and

n2 = 2ij + 3k.

Now we form the cross product:

 

= –11i – 19j + k

Now we need a point A on the line. Let's set x to 0 in each equation and solve for yA and zA.

From P1: 0 – 3yA –2zA = 7

From P2: 0 – yA + 3zA = 4

Solving, we get

, and .

We can use this point in setting up the equations of the line:

x = 0 –11t, y = –29/11 – 19t, z = 5/11 + t

or in symmetric form,


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General Contents

Detailed Contents

Index