Cones - Overview

Auteur :Christine

Thème :Cône

Cone Facts: Notice these interesting things:

It has a flat base
It has one curved side

The pointy end of a cone is called the apex
The flat part is the base
An object shaped like a cone is said to be conical

Surface Area of a Cone:

The Surface Area has two parts:

The Base Area = π × r²
The Side Area = π × r × s

Which together makes: Surface Area = π × r × (r + s) Note: we can calculate s = √(r²+h²) Example: h = 7 and r = 2 Surface Area of Base= π × r² = π × 2² = 4π ≈ 12.57 Surface Area of Side= π × r × √(r²+h²) = π × 2 × √(2²+7²) = π × 2 × √(4+49) = 2π√(53) ≈ 45.74 Total Surface Area ≈ 12.57 + 45.74 ≈ 58.31 Volume of a Cone: Volume = 1/3 π × r²× h Example: h = 7 and r = 2 Volume= 13 π × r² × h = 13 π × 2² × 7 = 283 π ≈ 29.32 Volume of a Cone vs Cylinder:

The volume formulas for cones and cylinders are very similar:

The volume of a cylinder is:	π × r²× h
The volume of a cone is:	1/3 π × r²× h

So a cone's volume is exactly one third ( 13 ) of a cylinder's volume. Different Shaped Cones:

Construction Cone

This is almost a cone, but the top is chopped off (called a "truncated cone"). Also it has a wider base added so it doesn't fall over!

Cones - Overview

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