Exploring the Volume and Surface Area of Cones: Key Concepts and Examples
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In this lesson, we will explore the volume and surface area of cones through engaging examples and practice problems. Learn how to sketch and label a cone, calculate its surface area, and determine its volume using the formula ( V = frac{1}{3} pi r^2 h ). We will work through real-life applications, including calculating the height of a cone-shaped party hat from its volume. Finally, we will compare cones and cylinders to understand their relationships in geometry. Dive into the world of geometry with these practical exercises!
Exploring the Volume and Surface Area of Cones: Key Concepts and Examples
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Presentation Transcript
Lesson 21 Surface Area & Volume Volume of Cones
Warm-Up • Sketch and label a diagram of a cone with a radius of 3 cm and a height of 7 cm. • Find the surface area of the cone in #1. • A cone and a cylinder have congruent bases and are the same height. Predict what the relationship between their volumes will be.
Volume of Cones Target: Calculate the volume of cones.
Volume of a Cone The volume of a cone is equal to one-third of the product of the area of the base (B) and the height (h).
Example 1 Find the volume of the cone. Use 3.14 for π. • Write the formula. V = πr2h • Substitute known values. V ≈ (3.14)(4)2(12) • Find the value of the power. V ≈ (3.14)(16)(12) • Multiply. V ≈ 200.96 • The volume of the cone is about 200.96 cm3.
Example 2 Chantel helped with her sister’s party. Each child received a party hat full of treats. Each hat had a volume of 65.94 cubic inches. The radius of each hat was 3 inches. How tall was each party hat? • Write the formula. V = πr2h • Substitute known values. 65.94 ≈ (3.14)(3)2h • Find the value of the power. 65.94 ≈ (3.14)(9)h • Multiply. 65.94 ≈ 9.42h • Divide by 9.42 on both sides. 9.42 9.42 7 ≈ h • Each party hat was about 7 inches tall.
Exit Problems • Find the volume of the cone. Use 3.14 for . • A cone has a volume of 30 cubic inches. What is the volume of a cylinder with the same height and a congruent base to the cone?
Communication Prompt What is similar about cones and pyramids? What is different?