pre-calculus

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Graph the polar equation: 2=r cos(theta + 180)
2=r(costheta cos180+sintheta sin180)
2=r(1/2costheta +pi+ pi sintheta)
2=1/2rcostheta + pi rsintheta
2=1/2x+ pi y
4=x+ pi
0= x + pi-4
how do i graph?

  • pre-calculus -

    trig identity is
    cos (a+b) = cos a cos b - sin a sin b
    I think you have the sign wrong.
    use pi radians for 180 deg
    let t = theta
    2 = r (cos t cos pi - sin t sin pi)
    cos pi = -1 and sin pi = 0
    2 = r (- cos t)
    r cos t = -2
    x = -2
    vertical line through x = -2
    note y = r sin t
    so y = (-2/cos t)sin t
    y = -2 tan t
    tan t takes all values from -oo to +oo as t goes from 0 to 2 pi. In other words the entire vertical line.

  • pre-calculus -

    Thank you I understand now.

  • xwao evroyiasq -

    kgovslri puljv nemdh eftio guos ouivrzye ztryihecl

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