I cannot solve this problem, someone please help!?

Its for the radius with the equation:

1485.0316= 2*3.14*r^2+2*3.14*r*11.4

2 Answers

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  • Anonymous
    1 decade ago
    Favorite Answer

    1485.0316= 2*3.14*r^2+2*3.14*r*11.4

    1485.0316= 6.28*r^2+71.592*r

    6.28*r^2 + 71.592*r - 1485.0316 =0

    Discriminant =

    (71.592)^2 +4(1485.0316)(6.28) = 42429.41

    r1 = (-71.592 + 205.98) /12.56 = 10.7

    r2 = (-71.592 - 205.98) /12.56 = negative (rejected)

  • 1 decade ago

    i am not sure if your equation is right, but if it is as you have written it, the solution is simple;

    1485.0316 = 2*3.14*r^2 + 2*3.14*r*11.4

    1485.0316/(2*3.14) = r^2 + 11.4r

    236.47 = r^2 + 11.4r

    r^2 + 11.4r - 236.47 = 0 (quadratic equation)

    you get the value for r;

    r = 10.7 & r = -22.1

    since you do not have a negative number for radius;

    answer is r = 10.7

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