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Let D be the region in the first quadrant of the plane inside the limaçon r =7+5cos(theta) Find the volume?

Let D be the region in the first quadrant of the plane inside the limaçon r = 7+5cos(theta) Find the volume of the solid with base D that lies under the surface z = r^(1)sin(theta)

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  • kb
    Lv 7
    8 years ago
    Favorite Answer

    V = ∫∫ z dA

    ...= ∫(θ = 0 to π/2) ∫(r = 0 to 7 + 5 cos θ) (r sin θ) * (r dr dθ), via polar coordinates

    ...= ∫(θ = 0 to π/2) (1/3)r^3 sin θ {for r = 0 to 7 + 5 cos θ} dθ

    ...= ∫(θ = 0 to π/2) (1/3)(7 + 5 cos θ)^3 sin θ dθ

    ...= ∫(u = 12 to 7) (1/3)u^3 * (-1/5) du, letting u = 7 + 5 cos θ

    ...= ∫(u = 7 to 12) (1/15) u^3 du

    ...= (1/60)u^4 {for u = 7 to 12}

    ...= 3667/12.

    I hope this helps!

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