7th Grade Math

Get ConnectED

Volume

PART A BCDEF

Multi-Part

Lesson 1

Addresses

GLE 0706.1.3.

Main Idea

Find the volume of

cones.

Vocabulary

cone

Volume of Cones

CANDLE MAKING Grace and Elle are making

candles to donate for a school fundraiser. The

mold they are using is 6 inches tall and has a

radius of 3 inches.

1. What would be the volume of the candle if it was a cylinder, but
   had the same radius and height?


2. MAKE A CONJECTURE What fraction of the cylinder is the cone?

A cone is a three-dimensional figure with one circular base. A curved

surface connects the base and vertex.

Volume of a Cone

Words The volume V of a cone with

radius r is one third the area of

the base B times the height h.

Model

hr

Symbols V = ^13 Bh or V = ^13 πr^2 h

Volume of a Cone

Find the volume of the cone. Round to the nearest tenth.

V = _^1

3

πr^2 h Volume of a cone

3 in.

6 in.

V = _^1

3

· π · 32 · 6 r = 3, h = 6

V ≈ 56.5 Simplify.

The volume is about 56.5 cubic inches.

Find the volume of each cone. Round to the nearest tenth.

a.

2 ft

7 ft

b.

26 mm

24 mm

candl

The ≈ symbol is read is

about equal to.

V

c

Lesson 1F Volume 575

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