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A cone has a radius of 8 cm and a slant height of 10 cm. What is the surface area of the cone to the nearest tenth of a square centimeter? Use π ≈ 3.14.

A. 670.2 cm
B. 804.2 cm
C. 452.2 cm
D. 640 cm

1 Answer

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Final answer:

To calculate the surface area of a cone with a radius of 8 cm and a slant height of 10 cm, we find the lateral surface area and base area using the formulae with π ≈ 3.14, and then sum these areas to get approximately 452.2 cm², which corresponds to answer choice C.

Step-by-step explanation:

The surface area of a cone can be found using the formula for the lateral or side area plus the area of the base. The lateral surface area is given by the formula Alateral = πrl, where r is the radius and l is the slant height. The formula for the area of the circular base is Abase = πr². We are given the radius (r) is 8 cm, and the slant height (l) is 10 cm. Using π ≈ 3.14, we calculate the following:

  • Lateral Surface Area: Alateral = π*8 cm*10 cm ≈ 3.14*8*10 = 251.2 cm²
  • Base Area: Abase = π*8 cm² ≈ 3.14*64 = 201 cm²

Adding these two areas together gives us the total surface area of the cone: Atotal = Alateral + Abase = 251.2 cm² + 201 cm² ≈ 452.2 cm². Therefore, the correct answer is C. 452.2 cm², to the nearest tenth of a square centimeter.

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