15.3 - Spheres

Links and useful resources

• gr10's Geometry >>>START HERE<<<
• AoPS Online Textbook
• AoPS Alcumus
• Big Ideas Geometry textbook
• GeoGebra Online Geometry Constuction Tool
• Two-column math templates
• Proofs unit slides from mathgiraffe.com
• Proofs unit printables for two-column proofs

Concept summary and connections

• Volume of a sphere: $\frac{4}{3}\pi r^3$
• Surface area of a sphere: $\pi r^2$
• Great circles
• Intersecting a plane and a sphere.

Guided practice

• A sphere of radius 12 cm is cut by a plane that passes within 6 cm of the center of the sphere. What is the perimeter of the shape of the intersection?
• The density of aluminum is 2.7 grams per cubic centimeter. If you made a solid cylinder of aluminum so that it was as small as possible while still having a spherical hole in the center with radius 10 cm, how much would it weigh?

Homework

• #hw (geom-gr10) 15.3 Spheres (p. 390) (gr10) 2025-03-20