15.2 - Cones

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

• A cone is a round pyramid...
• Volume of a cone: $\frac{1}{3}\pi r^{2}h$
• Surface area of a cone: $\pi rl$ where $l$ is the slant height of the cone.

Lesson and worked examples

Media resources

• Youtube search for "A cone is a round pyramid..."
• Youtube search for "Volume of a cone: $\frac{1}{3}\pi r^{2}h$"
• Youtube search for "Surface area of a cone: $\pi rl$ where $l$ is the slant height of the cone."

Guided practice

• Show that the lateral surface area of a cone is $\pi rl$
• Find the volume of a right circular cone that has radius 6 and slant height 8.

Homework

• #hw (geom-gr10) 15.2 Cones (p. 385) (gr10) 2025-03-14