If the base of a prism is a polygon having more than four vertices, it might be easier to calculate the area, if you divide the base into polygons with fewer vertices.
If the base, for instance, is either a triangle or a rectangle, you can just calculate the area directly.
However, if the base is a more complex polygon, you’ll have to divide it into triangles, and then calculate the area of each triangle.
Or you can use the formula for area of regular polygons, as long as it is a n-sided polygon with equal sides and angles:
Where A is the area, n is the number of sides, and b is the side length.
Use the following formula instead, if your calculator hasn't got the cotangent feature.