Math

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the formula for the surface area of a cylinder is: A=2πrh+2πr^2 If the height of the cylinder is 10 inches, and the surface area is 200 sq. inches, determine the length of the radius

  • Math -

    A = 2 ð r h + 2 ð r ^ 2


    2 ð r 10 + 2 ð r ^ 2 = 200 Divide both sides by 2 ð

    10 r + r ^ 2 = 100 / ð

    r ^ 2 + 10 r - 100 / ð = 0


    100 / ð = 31.831


    Y>ou nust solve equation :

    r ^ 2 + 10 r - 31.831 = 0

    The solutions are :

    2.54 in

    and - 12.54 in

    Radius can't be negative, so soution are:

    r = 2.54 in


    P.S.

    If you don't know how to solve equation

    In google type:

    quadratic equation online

    When you see list of results click on:

    Free Online Quadratic Equation Solver:Solve by Quadratic Formula

    When page be open in rectangle type:

    r ^ 2 + 10 r - 31.831 = 0

    and click option: solve it

    You will see solution step-by step

  • Math -

    ð = pi

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