Key Points
Surface Areas And Volumes
Surface Area and Volume of a Cuboid
For a cuboid with length , breadth , and height : Lateral Surface Area (LSA) is , Total Surface Area (TSA) is , and Volume is .
Surface Area and Volume of a Cube
For a cube with edge length : Lateral Surface Area (LSA) is , Total Surface Area (TSA) is , and Volume is .
Surface Area and Volume of a Cylinder
For a right circular cylinder with radius and height : Curved Surface Area (CSA) is , Total Surface Area (TSA) is , and Volume is .
Surface Area and Volume of a Cone
For a right circular cone with radius , height , and slant height : Curved Surface Area (CSA) is , Total Surface Area (TSA) is , and Volume is .
Slant Height of a Cone
The slant height of a cone is found using the Pythagorean theorem with its radius and height . The formula is .
Surface Area and Volume of a Sphere
For a sphere with radius : Surface Area is and Volume is . A sphere has only one continuous curved surface.
Surface Area and Volume of a Hemisphere
For a hemisphere with radius : Curved Surface Area (CSA) is , Total Surface Area (TSA) is (CSA + base area), and Volume is .
Principle of Surface Area of Combined Solids
To find the surface area of a combined solid, add the areas of all visible surfaces. Do not include the areas of the faces where the solids are joined together, as they are no longer exposed.
Principle of Volume of Combined Solids
To find the volume of a combined solid, simply add the volumes of the individual component solids. If a solid is hollowed out, subtract the volume of the removed portion.
Surface Area of a Toy (Cone on Hemisphere)
For a toy made of a cone mounted on a hemisphere of the same radius , the total surface area is the sum of their curved surface areas. TSA = (CSA of cone) + (CSA of hemisphere) = .
Surface Area of a Capsule
A capsule is a cylinder with two hemispheres at its ends. Its total surface area is the CSA of the cylinder plus the CSA of the two hemispheres. TSA = .
Surface Area of a Cube with Hemisphere on Top
The surface area is the TSA of the cube, minus the base area of the hemisphere (which is covered), plus the CSA of the hemisphere. TSA = .
Surface Area of a Solid with a Cavity
When a shape is hollowed out (e.g., a conical cavity from a cylinder), the surface area increases. The new total area = (CSA of original solid) + (Area of base) + (CSA of the hollowed-out shape).
Volume of a Toy (Cone on Hemisphere)
The volume of a toy composed of a cone mounted on a hemisphere is the sum of their individual volumes. Total Volume = (Volume of cone) + (Volume of hemisphere) = .
Volume of a Solid with a Cavity
If a shape is hollowed out from a solid (e.g., conical depressions in a cuboid), the volume of the remaining solid is the volume of the original solid minus the volume of the removed parts.
Quick Revision Tips
- • Review these points before exams
- • Make flashcards for better retention
- • Connect points to real-world examples
- • Practice explaining each point in your own words