Calculating the Surface Area of a Cone

Oct 13, 2025 by wbrum.org 73 views

The diameter of a cone's circular base measures 10 inches, and the slant height of the cone is 8 inches. What is the approximate surface area of the cone?

The surface area of a cone is the total area of its surface, including the circular base and the curved lateral surface. To calculate the surface area of a cone, we need to find the area of the circular base and the area of the curved lateral surface, and then add them together.

Calculating the Surface Area of a Cone

The formula for the surface area of a cone is:

A = πr(r + l)

where A is the surface area, π is a mathematical constant approximately equal to 3.14, r is the radius of the circular base, and l is the slant height of the cone.

Finding the Radius of the Circular Base

Given that the diameter of the circular base is 10 inches, we can find the radius by dividing the diameter by 2:

r = 10/2 = 5 inches

Finding the Surface Area of the Circular Base

The area of the circular base is given by the formula:

A_base = πr^2

Substituting the value of r, we get:

A_base = π(5)^2 = 3.14(25) = 78.5 in^2

Finding the Surface Area of the Curved Lateral Surface

The area of the curved lateral surface is given by the formula:

A_lateral = πrl

Substituting the values of r and l, we get:

A_lateral = π(5)(8) = 3.14(40) = 125.6 in^2

Finding the Total Surface Area of the Cone

The total surface area of the cone is the sum of the area of the circular base and the area of the curved lateral surface:

A_total = A_base + A_lateral = 78.5 + 125.6 = 204.1 in^2

Conclusion

Therefore, the approximate surface area of the cone is 204.1 in^2.

Comparison with the Given Options

Comparing our result with the given options, we can see that the correct answer is:

B. ${ $204.1 \, \text{in}^2\$}$

Final Answer

The final answer is 204.1.
The diameter of a cone's circular base measures 10 inches, and the slant height of the cone is 8 inches. What is the approximate surface area of the cone?

Calculating the Surface Area of a Cone

The formula for the surface area of a cone is:

A = πr(r + l)

where A is the surface area, π is a mathematical constant approximately equal to 3.14, r is the radius of the circular base, and l is the slant height of the cone.

Finding the Radius of the Circular Base

Given that the diameter of the circular base is 10 inches, we can find the radius by dividing the diameter by 2:

r = 10/2 = 5 inches

Finding the Surface Area of the Circular Base

The area of the circular base is given by the formula:

A_base = πr^2

Substituting the value of r, we get:

A_base = π(5)^2 = 3.14(25) = 78.5 in^2

Finding the Surface Area of the Curved Lateral Surface

The area of the curved lateral surface is given by the formula:

A_lateral = πrl

Substituting the values of r and l, we get:

A_lateral = π(5)(8) = 3.14(40) = 125.6 in^2

Finding the Total Surface Area of the Cone

The total surface area of the cone is the sum of the area of the circular base and the area of the curved lateral surface:

A_total = A_base + A_lateral = 78.5 + 125.6 = 204.1 in^2

Conclusion

Therefore, the approximate surface area of the cone is 204.1 in^2.

Comparison with the Given Options

Comparing our result with the given options, we can see that the correct answer is:

B. ${ $204.1 \, \text{in}^2\$}$

Final Answer

The final answer is 204.1.

Q: What is the formula for the surface area of a cone?

A: The formula for the surface area of a cone is A = πr(r + l), where A is the surface area, π is a mathematical constant approximately equal to 3.14, r is the radius of the circular base, and l is the slant height of the cone.

Q: How do I find the radius of the circular base of a cone?

A: To find the radius of the circular base of a cone, you need to divide the diameter of the circular base by 2.

Q: What is the area of the circular base of a cone?

A: The area of the circular base of a cone is given by the formula A_base = πr^2, where r is the radius of the circular base.

Q: What is the area of the curved lateral surface of a cone?

A: The area of the curved lateral surface of a cone is given by the formula A_lateral = πrl, where r is the radius of the circular base and l is the slant height of the cone.

Q: How do I find the total surface area of a cone?

A: To find the total surface area of a cone, you need to add the area of the circular base and the area of the curved lateral surface.

Q: What is the approximate surface area of a cone with a diameter of 10 inches and a slant height of 8 inches?

A: The approximate surface area of a cone with a diameter of 10 inches and a slant height of 8 inches is 204.1 in^2.

Q: What is the final answer to the problem?

A: The final answer to the problem is 204.1.