# double integral in vector calculus

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• June 21st 2008, 04:03 AM
^_^Engineer_Adam^_^
double integral in vector calculus
A field is given G = $\frac{25}{x^2+y^2}(x\hat{a}_x + y\hat{a}_y)$
Find
a.) unit vector in the direction G at (3,4,-2)
already answered :
by substitution
3a_x + 4a_y so unit vector is:
0.6a_x + 0.8a_y
b.) the angle between G and a_x at P
already answered :
arctan of (0.8/0.6)

this is my problem:
c.)Find the value of the double integral on the plane y = 7
i dont know how the limits are found
can someone help?

ans. 26
• June 23rd 2008, 06:01 AM
^_^Engineer_Adam^_^
the following solution is correct:
$\int_{0}^{4}\int_{0}^{2} G \hat{a}_{y} dz dx$
does anyone know how the limits are found?