# Sphere and surface area

From astronomers determining that Earth was in fact round and not a flat disc, cube or zigguratto the first successful attempts at circumnavigation, our estimates have changed over time. Links Forward Areas We can now find the areas of the basic figures of geometry. To make sense of the area of a figure that is not bounded either by straight lines or circular arcs, we need integral calculus.

While these ideas go back to Archimedes and Eudoxus, the systematic development of integral calculus is due to Newton and Leibniz. We can use trigonometry, to find the areas of various figures given enough information about their sides and angles.

## Ball Surface Area

This formula holds for pyramids with a polygonal base with area A. The cross-sections of a cone or sphere are circles but the radii of the cross-sections differ. The volume of a cone is one third of the volume of the corresponding cylinder with the same height and radius.

This completes the volume formulas for the basic solids. Solids with irregular boundaries can be dealt with using integral calculus.

These are all treated in the module, Cones, Pyramids and Spheres. For example, trapezium despite the Latin ending comes from the Greek word for table, while prism is derived from a Greek word meaning to saw since the cross-sections, or cuts, are congruentalso the word cylinder is from a Greek word meaning to roll.

The ancient Greeks were the first to systematically investigate the areas and volumes of plane figures and solids. During the Hellenistic Period, the great mathematician Archimedes c.

He also derived the formulas for the volume and surface area of the sphere. Thus, an oblique prism has parallel horizontal base and top but the sides are not vertical.

Such a solid is called a parallelepiped another Greek word meaning parallel planes. The next big advance came with integral calculus, when sense could be made of the concept of area under a curve using the ideas of a limit.

Although much progress had been made on this by Fermat and Descartes, it was the independent work of Newton and Leibniz that led to the modern theory of integration. There are approximate methods for finding the area of a figure with an irregular boundary.

This rule enables us to find an approximate value of the area of an irregular figure by taking measurements across the figure at various points along some axis. It is used today by cardiologists in measuring, for example, the right ventricular RV volume relating to blood flow in the heart.A three-dimensional circle is known as a sphere.

In order to calculate either the surface area or the volume of a sphere, you need to know the radius (r).The radius is the distance from the center of the sphere to the edge and it is always the same, no matter which points on the sphere. Content. Area of a parallelogram.

A parallelogram is a quadrilateral with opposite sides equal and parallel. We can easily find the area of a parallelogram, given its base b and its height h. In the diagram below, we draw in the diagonal BD and divide the figure into two triangles, each with base length b and height h.

Since the area of each triangle is bh the total area A is given by. The surface area of a solid object is a measure of the total area that the surface of the object occupies.

The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of arc length of one-dimensional curves, or of the surface area for polyhedra (i.e., objects with flat polygonal faces), for which the surface area is the sum.

The surface area of a sphere is given by the formula Where r is the radius of the sphere. In the figure above, drag the orange dot to change the radius of the sphere and note how the formula is used to calculate the surface area. If a solid is composed of flat surfaces, such as the cube on the right, the surface area is simply the sum of the areas of the flat surfaces (called faces). Whereas S equals the surface area, c represents the distance from the center to a pole, and a represents the semi-axis, e represents the eccentricity.

Naturally, Earth’s surface area can also be.

Sphere - Wikipedia