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**Flowers4Carlos****Member**- Registered: 2005-08-25
- Posts: 106

please help me out on this one!! i've been looking at the problem for hours now and i can't figure it out

find a vector function that represents the curve of intersection of the two surfaces

the cone z = (x² + y²)^(1/2) and the plane z = 1 + y

answer: r(t) = ti + 1/2*(t² - 1)j + 1/2(t² + 1)k

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**Flowers4Carlos****Member**- Registered: 2005-08-25
- Posts: 106

hmm... well the book did give one lousy example:

find a vector function that represents the curve of intersection of the cylinder x² + y² = 1 and the plane y + z = 2

answer: the projection of C (curve of intersection) onto the xy plane is the circle x² + y² = 1, z=0. so we know that we can write

x=cost y=sint 0≤t≤2pi

from the equation of the plane we have z = 2 - y = 2 - sint

so we can write parametric equations for C as

x=cost y=sint z= 2 - sint 0≤t≤2pi

the corresponding vector equation is

r(t) = costi + sintj + (2-sint)k 0≤t≤2pi

i hope someone can make sense out of it.

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