- #1
Mare102
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Homework Statement
I'm trying to find the center of mass of the region (x²+y²)² =2xy in the first quadrant, but I got stuck.
The Attempt at a Solution
What I did is make the substitution x = r cos(t), y = r sin(t), which gives the equation [tex]r^{4}=2r²cos(t) sin(t)[/tex], so r² = sin(2t), so [tex]r=\sqrt{sin(2t)}[/tex].
Then the integral for the area of the region becomes (as the Jacobian is r)
[tex]\int_0^{\pi/2} \int_0^{\sqrt{sin(2t)}} \! r \, dr dt[/tex]
Solving this gives me 0.5.
I’m trying to find the x value of the center of mass, so I want to solve:
[tex]\int_0^{\pi/2} \int_0^{\sqrt{sin(2t)}} \! r² cos(t) \, dr dt[/tex]
Which gives me
[tex]\int_0^{\pi/2} \! sin(2t)^{1.5} cos(t) \, dt[/tex]
Which I’m unable to solve. Mathematica gives me a complicated integral, so does anyone know how to proceed, or maybe suggest a different approach?