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Geometry

A cone has a slant height of 15cm. The true height is 12 and the radius "r" is unknown. True height 12 and the radius intersect at a perpendicular angle inside the cone. What is the surface area of the entire cone?

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  1. r^2 + 12^2 = 15^2
    r^2 = 225 - 144 = 81
    r = 4
    area of bottom = pi (16)
    area of sides = (1/2)(2 pi r) (L) = pi * 4 * 15
    total area = pi (16 + 60)

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  2. if r^2 = 81, r=9

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    oobleck

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