Geometry

The surface area of acone with height 15 cm is 500π square cm. Find the radius of the cone. Round your answer to two decimal places.

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  1. The surface area

    SA=Pi*r^2+Pi*r*s, s=sqrt(r^2+h^2)
    500*Pi=Pi*r^2+Pi*r*sqrt(r^2+225)
    500=r^2+r*sqrt(r^2+225)
    500-r^2=r*sqrt(r^2+225)
    (500-r^2)^2=(r*sqrt(r^2+225))^2
    250000-1000r^2+r^4=r^2(r^2+225)
    250000=1225r^2
    r^2=250000/1225

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