Surface Area of Cones

In this video, Mr. J explains how to find the surface area of a cone. The surface area is the total area of the outside of a three-dimensional shape. For cones, it involves calculating the area of the base and the lateral area, then adding them together. The formula used is pi r squared for the base and pi r s for the lateral area, where r is the radius and s is the slant height. An example is provided with a cone having a base radius of 4 inches and a slant height of 13 inches. The video walks through the calculation process, including using a calculator to find the surface area in terms of pi and in decimal form.

What is the surface area of a three-dimensional shape?

• The volume of the shape

• The height of the shape

• The area of the base only

• The total area of the outside surface

Which two areas are added to find the total surface area of a cone?

• Base area and height

• Height and slant height

• Lateral area and volume

• Base area and lateral area

In the formula for the surface area of a cone, what does 'r' represent?

• Diameter of the base

• Slant height

• Height of the cone

• Radius of the base

What is the purpose of looking at the net of a cone?

• To find the height

• To determine the diameter

• To understand the surface area visually

• To calculate the volume

What is the formula for the lateral area of a cone?

• pi * r^2

• 2 * pi * r

• pi * r * s

• pi * r * h

In the example, what is the radius of the cone's base?

• 6 inches

• 5 inches

• 4 inches

• 3 inches

How is the area of the base expressed in terms of pi?

• 16 pi

• 52 pi

• 68 pi

• 4 pi

What is the final surface area of the cone in terms of pi?

• 100 pi

• 84 pi

• 68 pi

• 52 pi

What is the approximate decimal value of 68 pi rounded to the nearest hundredth?

• 213.63

• 214.00

• 220.75

• 210.50

Why might your calculated surface area differ slightly from the example?

• Calculating the volume instead

• Using an approximate value for pi

• Using a different radius

• Different slant height