Pyramids
A pyramid is a 3D shape with flat A plane surface of a geometric solid. A cube has 6 faces; a tetrahedron, 4 faces.. The base of a pyramid is a polygon and is used to describe the pyramid (eg a square-based pyramid, triangle-based pyramid etc). Its sides are triangles which meet at the top.
Volume
The volume of a pyramid can be calculated using the formula:
\(\text{volume of a pyramid} = \frac{1}{3} \times \text{area of base} \times \text{perpendicular height}\)
The If the angle between two lines is a right angle, the lines are said to be perpendicular. height (h) is the height of the pyramid measured at a right angle from the base.
Surface area
The surface area of a pyramid can be calculated by adding the area of the base to the sum of the areas of the triangular faces.
Question
Find the area of this square-based pyramid:
The area of the base is \(5 \times 5 = 25~cm^2\)
The area of each triangular face is \((5 \times 6) \div 2 = 15~cm^2\).
There are four identical triangular faces, so the total surface area is \(25 + 4 \times 15 = 85~cm^2\)