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Last updated on August 30, 2025
A polyhedron is a 3-dimensional shape with flat polygonal faces, straight edges, and vertices. The surface area of a polyhedron is the total area covered by its outer surface. In this article, we will learn about the surface area of polyhedra, including how to calculate it for various types of polyhedra.
The surface area of a polyhedron is the total area occupied by the boundary or surface of the polyhedron. It is measured in square units.
A polyhedron is a 3D shape with flat surfaces called faces, straight edges, and vertices.
Polyhedra can be classified into different types, including regular polyhedra (Platonic solids) and irregular polyhedra.
The surface area of a polyhedron is calculated by summing the areas of all its faces.
To calculate the surface area of a polyhedron, add up the areas of all its individual faces.
Each face is a polygon, and the area can be calculated based on the type of polygon (e.g., triangles, squares, rectangles).
The formula for the surface area of a polyhedron depends on the number and shape of its faces.
Regular polyhedra, also known as Platonic solids, have faces that are congruent regular polygons.
Examples include the tetrahedron, cube, and dodecahedron.
The surface area of a regular polyhedron can be calculated using the formula:
Surface Area = n × A
Here, n is the number of faces, and A is the area of one face.
For irregular polyhedra, the surface area is calculated by finding the area of each face and summing them up.
Since the faces may not be congruent or regular, each face might require a different method to calculate its area, depending on its shape.
The volume of a polyhedron shows how much space is inside it. It depends on the shape and size of the polyhedron.
For regular polyhedra, specific formulas based on the type of solid can be used to calculate volume.
For irregular polyhedra, methods like decomposition into simpler shapes or using calculus might be necessary.
Students sometimes confuse the number of faces with the number of edges. Remember that the surface area involves calculating the area of each face, not the length of edges.
A cube has 6 congruent square faces. Area of one face = 4 × 4 = 16 cm² Surface Area = 6 × 16 = 96 cm²
Calculate the surface area of a regular tetrahedron with each edge measuring 3 cm.
SA = 15.59 cm²
A regular tetrahedron has 4 equilateral triangle faces. Area of one face = (√3/4) × 3² = 3.897 cm² Surface Area = 4 × 3.897 = 15.59 cm²
A rectangular prism has dimensions 5 cm, 3 cm, and 2 cm. Find the surface area.
SA = 62 cm²
Surface Area = 2(lw + lh + wh) = 2(5×3 + 5×2 + 3×2) = 2(15 + 10 + 6) = 2 × 31 = 62 cm²
Find the surface area of a cylinder with a height of 8 cm and a base radius of 3 cm.
SA = 207.72 cm²
Surface Area = 2πr(h + r) = 2 × 3.14 × 3 × (8 + 3) = 6.28 × 3 × 11 = 207.72 cm²
Determine the surface area of a regular octahedron with an edge length of 2 cm.
SA = 13.86 cm²
Students often make mistakes while calculating the surface area of polyhedra, which leads to incorrect answers. Below are some common mistakes and the ways to avoid them.
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