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bugatti79
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Homework Statement
Use Green's Theorem to evaluate this line integral
Homework Equations
[itex]\int xe^{-2x}dx+(x^4+2x^2y^2)dy[/itex] for the annulus [itex]1 \le x^2+y^2 \le 4[/itex]
The Attempt at a Solution
[itex] \displaystyle \int_c f(x,y) dx + g(x,y)dy+ \int_s f(x,y) dx + g(x,y)dy = \int \int _D1 (G_x-G_y) dA=0 \implies \int_c=- \int_s= \int_{-s}[/itex]
Let c be the out circle of radius 2 counterclockwise and s the inner radius of 1 clockwise
x=r cos [itex]\theta[/itex], y=r sin [itex]\theta[/itex] substituting
evaluating the last term on RHS, ie
[itex] \displaystyle \int_{-s}= \int_0^{2 \pi} r cos \theta (e^{-2r cos \theta})(-r sin \theta d \theta) +(r^4 cos^4 \theta +2r^2 cos^2 \theta r^2 sin^2 \theta) r cos \theta d \theta[/itex]
Is this right so far? Thanks