Evaluating a Surface Integral: A Parallelogram

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The discussion focuses on evaluating a surface integral for a function defined over a parallelogram with specific parametric equations. Participants suggest using the formula for surface integrals, involving the cross product of partial derivatives and the function evaluated at the parametrization. There is a debate over the correct magnitude of the determinant, with one participant initially calculating it as √2, while another corrects it to √14. The latter also clarifies that the vector mentioned is not a determinant but rather a vector representation. The conversation emphasizes the importance of accurately calculating the determinant for the surface integral evaluation.
bugatti79
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Homework Statement



Evlute the surface integral

Homework Equations



f(x,y,z)=x+y+z where sigma is the parallelogram with parametric equations x=u+v, y=u-v and z=1+2u+v where 0 <=u<=2 and 0<=v<=1.



The Attempt at a Solution



I have no idea how to tackle this. Any suggestions?
 
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bugatti79 said:

Homework Statement



Evlute the surface integral

Homework Equations



f(x,y,z)=x+y+z where sigma is the parallelogram with parametric equations x=u+v, y=u-v and z=1+2u+v where 0 <=u<=2 and 0<=v<=1.



The Attempt at a Solution



I have no idea how to tackle this. Any suggestions?

You might begin by studying the material at:

http://tutorial.math.lamar.edu/Classes/CalcIII/SurfaceIntegrals.aspx
 
LCKurtz said:
You might begin by studying the material at:

http://tutorial.math.lamar.edu/Classes/CalcIII/SurfaceIntegrals.aspx

I believe we have to use \displaystyle \int \int _R f(x(u,v),y(u,v), z(u,v) || r_u \times r_v||dA

I calculate the magnitude of the determinent to be \sqrt 2 hence

The surface integral becomes

\displaystyle \sqrt{2} \int_{0}^{1} \int_{0}^{2} (4u+v+1) du dv...?
 
I agree with everything except the ##\sqrt 2##.
 
LCKurtz said:
I agree with everything except the ##\sqrt 2##.

since we have the determinant as 3i+1j-2k and the magnitude is

\sqrt(3^2+(-2^2)+1)=\sqrt 14 cheers
 
bugatti79 said:
since we have the determinant as 3i+1j-2k and the magnitude is

\sqrt(3^2+(-2^2)+1)=\sqrt 14 cheers

The ##\sqrt {14}## is correct, but 3i + j - 2k is not a determinant; it is a vector.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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