Key Points

Surface Areas And Volumes

15 Sections
  • Surface Area and Volume of a Cuboid

    For a cuboid with length ll, breadth bb, and height hh: Lateral Surface Area (LSA) is 2(l+b)h2(l+b)h, Total Surface Area (TSA) is 2(lb+bh+hl)2(lb + bh + hl), and Volume is V=l×b×hV = l \times b \times h.

  • Surface Area and Volume of a Cube

    For a cube with edge length aa: Lateral Surface Area (LSA) is 4a24a^2, Total Surface Area (TSA) is 6a26a^2, and Volume is V=a3V = a^3.

  • Surface Area and Volume of a Cylinder

    For a right circular cylinder with radius rr and height hh: Curved Surface Area (CSA) is 2πrh2\pi rh, Total Surface Area (TSA) is 2πr(r+h)2\pi r(r+h), and Volume is V=πr2hV = \pi r^2 h.

  • Surface Area and Volume of a Cone

    For a right circular cone with radius rr, height hh, and slant height ll: Curved Surface Area (CSA) is πrl\pi rl, Total Surface Area (TSA) is πr(r+l)\pi r(r+l), and Volume is V=13πr2hV = \frac{1}{3}\pi r^2 h.

  • Slant Height of a Cone

    The slant height ll of a cone is found using the Pythagorean theorem with its radius rr and height hh. The formula is l=r2+h2l = \sqrt{r^2 + h^2}.

  • Surface Area and Volume of a Sphere

    For a sphere with radius rr: Surface Area is 4πr24\pi r^2 and Volume is V=43πr3V = \frac{4}{3}\pi r^3. A sphere has only one continuous curved surface.

  • Surface Area and Volume of a Hemisphere

    For a hemisphere with radius rr: Curved Surface Area (CSA) is 2πr22\pi r^2, Total Surface Area (TSA) is 3πr23\pi r^2 (CSA + base area), and Volume is V=23πr3V = \frac{2}{3}\pi r^3.

  • 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 rr, the total surface area is the sum of their curved surface areas. TSA = (CSA of cone) + (CSA of hemisphere) = πrl+2πr2\pi rl + 2\pi r^2.

  • 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 = 2πrh+2(2πr2)=2πr(h+2r)2\pi rh + 2(2\pi r^2) = 2\pi r(h + 2r).

  • 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 = 6(edge)2πr2+2πr2=6(edge)2+πr26(\text{edge})^2 - \pi r^2 + 2\pi r^2 = 6(\text{edge})^2 + \pi r^2.

  • 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) = 13πr2h+23πr3\frac{1}{3}\pi r^2 h + \frac{2}{3}\pi r^3.

  • 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.

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