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how do you convert 2x^2-2y^2=5y to polar form?

I know how you factor out a 2 to get x^2-y^2=(5/2)y but I get stuck there. I can do it if it's x^2+y^2 but I don't know how to with the (-) sign

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  • Favorite Answer

    x = r * cos(t)

    y = r * sin(t)

    2 * (r * cos(t))^2 - 2 * (r * sin(t))^2 = 5 * r * sin(t)

    2 * r^2 * cos(t)^2 - 2 * r^2 * sin(t)^2 = 5r * sin(t)

    2r^2 * (cos(t)^2 - sin(t)^2) = 5r * sin(t)

    2r^2 * cos(2t) = 5r * sin(t)

    r^2 = 5 * r * sin(t) / (2 * cos(2t))

    r = 5 * sin(t) / (2 * cos(2t))

    r = (5/2) * (sin(t) / cos(2t))

  • 1 decade ago

    well, x=rcost, and y=rsint in polar coordinates. (r=radius, t=theta)

    i would just simply plug in those two into the given equation

    2*(rcost)^2-2*(rsint)^2 = 5rsint

    2*r^2*((cost)^2 - (sint)^2) = 5*r*sint

    2*r*((cost)^2 - (sint)^2) = 5*sint

    that's about the best i can do, hope this helps

  • 1 decade ago

    x = r cos(t)

    y = r sin(t)

    2(r cos(t))^2 - 2(r sin(t))^2 = 5(r sin(t))

    2 r^2 cos^2(t) - 2 r^2 sin^2(t) = 5r sin(t)

    2r^2 (cos^2 (t) - sin^2 (t)) = 5r sin(t)

  • TomV
    Lv 7
    1 decade ago

    x = RcosΘ

    y = RsinΘ

    2x² - 2y² = 5y

    2R²cos²Θ - 2R²sin²Θ = 5RsinΘ

    2R²(cos²Θ - sin²Θ = 5RsinΘ

    2R(1 - 2sin²Θ) = 5sinΘ

    2R = 5sinΘ/(1 - 2sin²Θ)

    R = 5sinΘ/(2cos2Θ)

    ...

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  • 1 decade ago

    are you doing summer work for mr. jones bc calc?

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