Question

The total surface area of a cone that has a base radious of 7cm is 417.8cm2 . calculate its slant height

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Answer 1

12 cm

Explanation:

The total surface area of the cone = area of base + area of curved surface

Subtract the base area from total area, that is

πrs = area - πr²

r is the radius and s the slant height

πrs = 417.8 - (π × 7²) = 263.86

Divide both sides by πr

s =
`(263.86)/(7\pi )` ≈ 12 cm