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Recall the formula for the lateral area of a right cone.
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We are asked find the amount of paper that is needed to make a drinking cup from the given diagram.
The cup is in the shape of a right circular cone. Therefore, the amount of paper needed to make the cup is equal to the lateral area of the cone. Let's recall the formula for the lateral area.
The lateral area L of a right circular cone is L=πrℓ, where r is the radius of the base and ℓ is the slant height. |
We know from the graph that the radius of the base is equal to 2.5 centimeters. To find the lateral area, we need to also know the cone's slant height ℓ. We can do that using the Pythagorean Theorem.
Substitute values
Calculate power
Add terms
Rearrange equation
LHS=RHS
a2=±a
Round to 2 decimal place(s)
r=2.5, ℓ=9.34
Multiply
Commutative Property of Multiplication
Use a calculator
Multiply
Round to 1 decimal place(s)