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ρ 3 cos θ = aρ 2 (cos 2 θ − sin 2 θ)<br />

<br />

cos 2θ<br />

ρ = a<br />

cos θ<br />

θ ∈ [−π/4, π/4] ∪ [π/2, 3/4π] ∪ [5/4π, 3/2π] x(θ) = ρ cos θ = a cos 2θ <br />

<br />

lim ρ = +∞ x = −a ρ(θ) = 0 θ =<br />

θ→±π/2∓ ±π/4 −π/4 < θ < π/4 0 < x < a |y| ≤<br />

x (a − x)/(a + x) C C <br />

<br />

<br />

C<br />

<br />

C<br />

dx dy =<br />

x dx dy =<br />

π/4 a cos(2θ)/ cos θ<br />

= a2<br />

2<br />

= a2<br />

2<br />

= a2<br />

2<br />

= a2<br />

2<br />

−π/4<br />

0<br />

π/4<br />

<br />

<br />

2<br />

2<br />

4 cos<br />

−π/4<br />

2 θ + 1<br />

π/4<br />

−π/4<br />

π/4<br />

−π/4<br />

(4 − π)<br />

π/4 a cos(2θ)/ cos θ<br />

= a3<br />

3<br />

= a3<br />

3<br />

= a3<br />

3<br />

= a3<br />

3<br />

= a3<br />

3<br />

−π/4 0<br />

π/4<br />

s ds dθ = a2<br />

2<br />

cos2 − 4 dθ<br />

θ<br />

π/4<br />

−π/4<br />

<br />

(cos 2θ + 1) dθ + [tan θ] π/4<br />

cos 2θ dθ + 2 − π<br />

<br />

−π/4<br />

π/4<br />

cos 2 (2θ)<br />

cos 2 θ dθ<br />

− 2π<br />

s 2 cos θ ds dθ = a3<br />

3 −π/4<br />

<br />

2 cos θ −<br />

−π/4<br />

1<br />

3 cos θ dθ<br />

cos θ<br />

π/4 <br />

8 cos<br />

−π/4<br />

4 θ − 12 cos 2 θ − 1<br />

cos2 <br />

+ 6 dθ<br />

θ<br />

<br />

π/4<br />

2(cos 2θ + 1)<br />

−π/4<br />

2 dθ − 3(2 + π) − 2 + 3π<br />

π/4<br />

<br />

cos 3 (2θ)<br />

cos 2 θ dθ<br />

2(cos<br />

−π/4<br />

2 2θ + 2 cos 2θ + 1) dθ − 3(2 + π) − 2 + 3π<br />

π/4<br />

(cos 4θ + 1 + 4 cos 2θ) dθ + π − 8<br />

−π/4<br />

= a3<br />

π/4<br />

(cos 4θ) dθ +<br />

3 −π/4<br />

3<br />

<br />

π − 4<br />

2<br />

= a3<br />

<br />

3<br />

π − 4 =<br />

3 2 a3<br />

(3π − 8)<br />

6<br />

<br />

<br />

x dx dy<br />

C<br />

xB = =<br />

dx dy<br />

a 3π − 8<br />

3 4 − π , yB = 0.<br />

C

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