मराठी
Maharashtra State BoardSSC (English Medium) 9th Standard

Mensuration of Cones

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Topics

  • Definition: Cone
  • Types of Cones
  • Properties of a Cone
  • Activity
CISCE: Class 10

Definition: Cone

The solid obtained on revolving a right-angled triangle about one of its sides (other than the hypotenuse) is called a cone or a right circular cone.

CISCE: Class 10

Formula: Cone

  • Volume = \[\frac{1}{3}\pi r^2h\]
  • Curved (lateral) surface area = πrl or \[\pi r\sqrt{h^{2}+r^{2}}\]
    (\[l=\sqrt{h^2+r^2}\])

  • Total surface area =

Structure and Types of Cones with Examples

Parts of a cone:

  1. Apex:
    The pointed tip is at the top of the cone.
  2. Curved Face:
    The curved face is a smooth, rounded surface that extends from the base to the apex.
  3. Circular Flat Face:
    The flat, circular base is present at the bottom of closed cones.
  4. Circular Edge:
    This term refers to the line that separates the curved face from the circular base.

Types of Cone:
Closed Cone :
A closed cone consists of one curved face, one flat circular face, and one circular edge.
Example: Ice cream cone (closed)

Open Cone :
An open cone features a curved face and a circular edge, but it lacks a flat face.
Example: clown’s cap

Maharashtra State Board: Class 6

Activity

Making a Cone from a Circle
Steps:

  1. Draw a Circle:
    Use a compass to draw a circle on paper with centre C.
  2. Mark Two Radii:
    Draw two lines from Centre C to the edge of the circle, naming them CR and CS (these are the radii).
  3. Cut Along the Radii:
    Cut the circle along both radii CR and CS to get two pieces.
  4. Form a Cone Shape:
    Take one piece and bring together the sides (CR and CS).
    Join them to form a cone shape.

Conclusion:
You get a cone from each piece of the circle by joining the two straight edges (radii).

Video Tutorials

We have provided more than 1 series of video tutorials for some topics to help you get a better understanding of the topic.

Series 1


Series 2


Series 3


Shaalaa.com | Volume of a Right Circular Cone

Shaalaa.com


Next video


Shaalaa.com


Volume of a Right Circular Cone [00:02:03]
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