"Side Area of ​​a Cone" Circle PPT Courseware

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"Side Area of ​​a Cone" Circle PPT Courseware

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Communicate cone-related concepts with peers

A cone is surrounded by a base and a side. Its base is a circle and the side is a curved surface.

Explore new knowledge

The side view of a cone is a fan shape

The radius of the sector: the generatrix of the cone

The arc length of the sector: the circumference of the cone base is 2πr

Area of ​​sector: side area of ​​cone

As shown in the figure, assuming that the length of the cone's generatrix is ​​l and the base radius is r, then the radius (R) of this sector is the cone's generatrix l,

The arc length (L) of the sector is the circumference of the cone base

Therefore, the side area of ​​the cone (S side) is half the product of the cone’s generatrix and the base perimeter.

Side area and total area of ​​a cone

The sum of the side area and base area of ​​a cone is called the total area of ​​the cone

The total area of ​​the cone = the side area of ​​the cone + the base area.

That is: S full = S side + S bottom = πrl + πr²

Lay a solid foundation

1. The base radius of the cone is r=4cm, the bus length is l=5cm, then the side area of ​​the cone is ___ square centimeters, the surface area is ___ square centimeters, and the central angle of the side expansion diagram is ___ degrees

2. The side area of ​​a cone with a height of 4� and a base diameter of 6�＿＿＿

3. If the cone’s generatrix l=10cm and its height h=8cm, then the central angle of the sector in the side expansion diagram is ＿＿＿

4. The angle between the cone's busbar and the height is 30°, and the busbar length is 6cm. Find its side area ____ and its total area ____

5. As shown in the figure, if the side expansion diagram of the cone is a semicircle, then the central angle of the expansion diagram is ___ degrees; the ratio r of the cone base radius r to the busbar l: l = ___; the vertex angle of the cone axis section is ___Spend.

Talk about your gains!

(1) The side expansion view of a cone is a fan shape

(2) The generatrix length of the cone is the radius of the sector

(3) The circumference of the cone base is the arc length of the sector

(4) The side area of ​​the cone is the area of ​​the sector

(5) The sum of the side area and the base area of ​​a cone is called the total area.

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"Side Area of ​​a Cone" Circle PPT Courseware 2:

"Side Area of ​​a Cone" Circle PPT Courseware 2 The formation of a cone: 1. A right-angled triangle rotates around a right-angled side 2. What is the side expansion diagram of a cone surrounded by a fan shape? It is a fan shape. Fill in the blanks according to the relationship between the fan shape and the cone: As shown in the figure, let the length of the generatrix of the cone be l and the base..

"Side Area and Total Area of ​​a Cone" Circle PPT Courseware 2:

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Update Time: 2024-11-25

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