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CBSE Class 9 Surface Areas and Volumes Complete Guide

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List of Surface Areas and Volumes Formulas with Solved Examples for Class 9

When it comes to studying Mathematics, the branch of Mensuration is considered to be one of the most practical branches. This is because Mensuration is the branch of Mathematics in which plane and solid figures like a cube, cuboid, sphere, cone, pyramid, etc. are studied with regards to their surface area and volume. For calculating this, there are specific formulas to be followed. Therefore, here in the Chapter Surface Area and Volume Class 9 by Vedantu, all formulas of the plane (2D) and solid (3D) figures shall be discussed.


The students who have Math as a subject have to keep up with certain topics of importance such as the Surface Areas and Volumes. It can be said that there are a few of the topics that are of utmost importance. The reason is mostly due to the fact that these concepts come in handy to the students at the time of their higher education. The topics such as these are ones which the students can find the most interesting as well. It is important for any class 9 student to have a good understanding of some of the most basic concepts that there are. This will definitely come in aid for them while they have to appear for their Math exams and score well in them. 


There are a few of the topics that come in handy while getting prepared for your exams. When it comes to the topics such as the surface areas and volumes, one can get all the formulas. It is important that the students get to understand the formulas and learn them as well. There are specific formulas that the students learn so that they can apply them as per their knowledge. 


All Formulas of Surface Area and Volume Class 9 - The Figures

As stated earlier, the field of Mensuration is concerned primarily with the study of solid and plane figures. These figures are three-dimensional in nature and are observed in nature. For example, if one were to understand and calculate the surface area of a Rubik’s cube, they would look at the formulated way of obtaining its surface area and then can successfully understand its surface area. Thus, through these Surface Area and Volume Class 9 Formulas, some of those figures shall be learned about with regards to their surface area and volume.


Since this field of study is concerned with the figures and their dimensional calculations, the formulas of Surface Area and Volume Class 9 are the ideal formulas for three-dimensional study. So, the formulas that are proposed through the study of mensuration are referred to understanding the ideal figures and their dimensions. However, since no real object imitating a pyramid is ever ideal or perfect, these Class 9 Surface Area and Volume Formulas do not obtain the absolute dimensional answers to real-life objects that imitate a plane or solid figure.


The Formula of Surface Area and Volume Class 9 - A Brief Analysis of the Figures

All the formulas of Surface Area and Volume Class 9 have been derived and deduced through a thorough understanding of the various contributing elements of the figures such as its length, breadth, height, circumference, etc. This Class 9 Surface Area and Volume Formula set have therefore been provided with regards to the figures of the cube, cuboid, right circular cylinder, right circular cone, sphere, and hemisphere. Therefore, these are the figures that the Surface Area and Volume Formulas Class 9 deals with.


Class 9 Maths Surface Area and Volume All Formulas - The Complete List

Cube

  • Surface Area: 6L2 where L is the dimension of its side.

  • Volume: L3 where L is the dimension of its side.

Cuboid

  • Surface Area: 2(LB+ BH+ LH).

  • Lateral Surface Area: 2(L + B) H (where L= Length, B= Breadth and H= Height)

  • Volume: LBH

Right Circular Cylinder

  • Lateral Surface Area: 2 \[ \pi RH \].

  • Total Surface Area:  \[2\pi R(H + R)\] 

  • Volume: \[\pi R^{2}H\] (where R= Radius, H= Height).

Right Circular Cone

  • Lateral Surface Area: \[ \pi RL \]

  • Total Surface Area: \[\rho \pi R(L + R)\]

  • Volume: \[\frac{2}{3}\pi R^{2}H\] (where R= Radius, L=Slant Height and H= Height)

Sphere

  • Surface Area: \[4\pi R^{2}\]

  • Volume:  \[\frac{4}{3}\pi R^{3}\](where R= Radius)

Hemisphere

  • Curved Surface Area: \[2\pi R^{2}\]

  • Total Surface Area: \[3\pi R^{2}\]

  • Volume: \[\frac{2}{3}\pi R^{3}\] (where R= Radius).


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FAQs on CBSE Class 9 Surface Areas and Volumes Complete Guide

1. What are the formulas for surface areas and volumes in Class 9 Maths?

The main formulas for Surface Areas and Volumes Class 9 include CSA, TSA, and volume of basic 3D shapes like cube, cuboid, cylinder, cone, and sphere.

  • Cuboid: TSA = 2(lb + bh + hl), Volume = l × b × h
  • Cube: TSA = 6a², Volume =
  • Cylinder: CSA = 2πrh, TSA = 2πr(r + h), Volume = πr²h
  • Cone: CSA = πrl, TSA = πr(l + r), Volume = ⅓πr²h
  • Sphere: Surface Area = 4πr², Volume = 4/3 πr³
These formulas are essential for solving problems related to mensuration in CBSE Class 9 Maths.

2. What is the difference between curved surface area and total surface area?

The curved surface area (CSA) includes only the curved part of a solid, while the total surface area (TSA) includes all surfaces including bases.

  • For a cylinder: CSA = 2πrh, TSA = 2πr(r + h)
  • For a cone: CSA = πrl, TSA = πr(l + r)
CSA excludes the circular top and bottom, whereas TSA includes every exposed surface.

3. What is the formula for the volume of a cylinder in Class 9?

The formula for the volume of a cylinder is πr²h.

  • r = radius of the base
  • h = height of the cylinder
Example: If r = 7 cm and h = 10 cm, then Volume = π × 7² × 10 = 490π ≈ 1540 cm³ (using π = 22/7).

4. How do you find the total surface area of a cube?

The total surface area of a cube is calculated using 6a², where a is the side length.

  • A cube has 6 equal square faces.
  • Area of one face = a²
  • TSA = 6 × a²
Example: If a = 5 cm, TSA = 6 × 25 = 150 cm².

5. What is the formula for the volume of a cone?

The volume of a cone is ⅓πr²h.

  • r = radius of the base
  • h = perpendicular height
Example: If r = 3 cm and h = 7 cm, Volume = ⅓ × π × 9 × 7 = 21π ≈ 66 cm³ (using π = 22/7).

6. What is the surface area of a sphere?

The surface area of a sphere is 4πr².

  • r = radius of the sphere
Example: If r = 7 cm, Surface Area = 4 × π × 49 = 196π ≈ 616 cm² (using π = 22/7). This formula is important in CBSE Class 9 mensuration problems.

7. How do you calculate the slant height of a cone?

The slant height of a cone is calculated using l = √(r² + h²).

  • r = radius
  • h = vertical height
This formula comes from the Pythagoras theorem. Example: If r = 6 cm and h = 8 cm, l = √(36 + 64) = √100 = 10 cm.

8. What is the formula for the volume of a sphere?

The volume of a sphere is 4/3 πr³.

  • r = radius of the sphere
Example: If r = 3 cm, Volume = 4/3 × π × 27 = 36π ≈ 113.14 cm³ (using π ≈ 3.14).

9. How do you find the total surface area of a cylinder?

The total surface area of a cylinder is 2πr(r + h).

  • r = radius of base
  • h = height
It includes both circular bases and the curved surface. Example: If r = 3 cm and h = 7 cm, TSA = 2π × 3 × (3 + 7) = 60π ≈ 188.4 cm² (using π ≈ 3.14).

10. What are the common mistakes students make in Surface Areas and Volumes?

The most common mistakes in Surface Areas and Volumes Class 9 involve using wrong formulas or incorrect units.

  • Confusing CSA with TSA
  • Forgetting to use in cone volume formula
  • Not squaring or cubing radius correctly (r², r³)
  • Mixing units (cm and m together)
  • Using wrong value of π (22/7 or 3.14)
Carefully checking formulas and units helps avoid calculation errors.