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How to solve these geometry problems?
For a party Louis has made 15,conical hates out of cardboard. if the total amount of cardboard used was 9,424.78 cm2 and each hat had a slant height of 20 cm, what is the radius of each hat?
(He gives us the answer which is 10 cm, i need help solving it)
1 Answer
- kenny kLv 67 years ago
pi r^2 + pr r l = area of a cone.
pi r^2 represents the base area, which we don't need. (Do you know why?)
9424.78 (total area ) / 15 (number of cones) = 628.3187 cm^2 (area of one cone)
3.14*r*20 = 628.3186... (substituting into formula)
20r = 200.00004... (divide by pi [3.14...])
r = 10.000002...
Rounded off, r = 10 cm
