Surface Area of Spheres and Hemispheres

The video tutorial covers the surface area of cones and spheres, providing formulas and examples for each. It explains the surface area of a cone, which includes the base and the slanted side, and the surface area of a sphere, which is four times the area of a circle with the same radius. Examples are given for calculating the surface area of a cone, a sphere, and a hemisphere, including a more complex example of a hemisphere with a lid. The tutorial emphasizes the importance of understanding and adapting formulas based on the shape's characteristics.

What are the two main shapes discussed in the video for surface area calculations?

• Cylinders and Cubes

• Cones and Spheres

• Pyramids and Prisms

• Cubes and Spheres

Which part of the cone does the formula πr² represent?

• The lateral surface

• The base circle

• The slant height

• The apex

What is the formula for the surface area of a sphere?

• 5πr²

• 4πr²

• 3πr²

• 2πr²

In the example, what is the radius of the cone used to calculate its surface area?

• 4

• 3

• 2

• 5

What is the calculated surface area of the cone in the example?

• 90.70

• 75.40

• 80.50

• 85.60

What is the radius of the sphere used in the example calculation?

• 22

• 20

• 18

• 24

What is the surface area of a sphere with a radius of 22?

• 6092.12

• 6082.12

• 6112.12

• 6102.12

What is the surface area of a hemisphere if the indicated surface area is 150 cm²?

• 150 cm²

• 75 cm²

• 225 cm²

• 300 cm²

How do you calculate the radius of a hemisphere given its surface area?

• Multiply by π and square root

• Divide by 2π and square root

• Multiply by 2π

• Divide by π

What is the radius of the hemisphere calculated in the example?

• 3.87 cm

• 6.87 cm

• 4.87 cm

• 5.87 cm