The area occupied by a three-dimensional object by its outer surface is called the surface area. A = l × √(l² + 4 × h²) + l² where l is a base side, and h is a height of a pyramidĪ = A(base) + A(lateral) = A(base) + 4 × A(lateral face) Practice Questions FAQs What is Surface Area The space occupied by a two-dimensional flat surface is called the area.The formula for the surface area of a pyramid is: That's the option that we used as a pyramid in this surface area calculator. Regular means that it has a regular polygon base and is a right pyramid (apex directly above the centroid of its base), and square – means that it has this shape as a base. But depending on the shape of the base, it could also be a hexagonal pyramid or a rectangular pyramid one. When you hear a pyramid, it's usually assumed to be a regular square pyramid. A = π × r × √(r² + h²) + π × r² given r and h.Ī pyramid is a 3D solid with a polygonal base and triangular lateral faces.From there, we’ll tackle trickier objects, such as cones and spheres. We’ll start with the volume and surface area of rectangular prisms. A = A(lateral) + A(base) = π × r × s + π × r² given r and s or 5 questions Koch snowflake fractal Herons formula Unit test 14 questions About this unit Volume and surface area help us measure the size of 3D objects.Finally, add the areas of the base and the lateral part to find the final formula for the surface area of a cone:.Thus, the lateral surface area formula looks as follows: R² + h²= s² so taking the square root we got s = √(r² + h²) But that's not a problem at all! We can easily transform the formula using Pythagorean theorem: Usually, we don't have the s value given but h, which is the cone's height.(sector area) = (π × s²) × (2 × π × r) / (2 × π × s)įor finding the missing term of this ratio, you can try out our ratio calculator, too! (sector area) / (large circle area) = (arc length) / (large circle circumference) so: The formula can be obtained from proportions, as the ratio of the areas of the shapes is the same as the ratio of the arc length to the circumference: The area of a sector - which is our lateral surface of a cone - is given by the formula:Ī(lateral) = (s × (arc length)) / 2 = (s × 2 × π × r) / 2 = π × r × s The arc length of the sector is equal to 2 × π × r. It's a circular sector, which is the part of a circle with radius s ( s is the cone's slant height).įor the circle with radius s, the circumference is equal to 2 × π × s. Let's have a look at this step-by-step derivation: The base is again the area of a circle A(base) = π × r², but the lateral surface area origins maybe not so obvious: For a shape drawn on a grid the area may be. A = A(lateral) + A(base), as we have only one base, in contrast to a cylinder. Key points A rectilinear shape may be a square or a rectangle or, as a compound shape, it can look like two or more rectangles joined together.We may split the surface area of a cone into two parts:
#Surface area of rectangle with square base how to#
Surface area of a pyramid: A = l × √(l² + 4 × h²) + l², where l is a side length of the square base and h is a height of a pyramid.īut where do those formulas come from? How to find the surface area of the basic 3D shapes? Keep reading, and you'll find out! Surface area of a triangular prism: A = 0.5 × √((a + b + c) × (-a + b + c) × (a - b + c) × (a + b - c)) + h × (a + b + c), where a, b and c are the lengths of three sides of the triangular prism base and h is a height (length) of the prism. Surface area of a rectangular prism (box): A = 2(ab + bc + ac), where a, b and c are the lengths of three sides of the cuboid. Surface area of a cone: A = πr² + πr√(r² + h²), where r is the radius and h is the height of the cone. Surface area of a cylinder: A = 2πr² + 2πrh, where r is the radius and h is the height of the cylinder. Surface area of a cube: A = 6a², where a is the side length.
Surface area of a sphere: A = 4πr², where r stands for the radius of the sphere. The formula depends on the type of solid.
Our surface area calculator can find the surface area of seven different solids.
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