a sector of a circle is used to make a hat shaped like a right cone. the cone has a height of 4 in. and a base diameter of 8 inches. the outside of the hat is to be covered in red crepe paper. determine the area that will be covered in crepe paper to the nearest square inch.
We can use the Pythagorean Theorem to find the "slant height" of the cone....note that the raduis of the cone = 4 inches
Slant Height = sqrt [ height^2 + radius^2] = sqrt [ 4^2 + 4^2 ] = sqrt [ 16 + 16 ] = sqrt [ 32] = 4sqrt (2) inches
The amount of crepe paper needed = the surface area of the cone = pi * radius * slant height =
pi * (4 inches) ( 4 sqrt (2) inches) =
pi * 16 sqrt (2) inches ^2 ≈ 71.086 in^2