Geometry deals heavily with polygons. Polygons are enclosed two-dimensional shapes that come in all forms and sizes. Geometry focuses almost entirely on simple polygons. Simple polygons, as opposed to complex polygons, do not cross over themselves.
Polygons can be further classified as regular or irregular. Regular polygons have sides of equal length, while the sides of irregular polygons are disproportionate. Polygons are mainly named by the number of sides they possess. The simplest polygon, the triangle, has three sides. A megagon, on the other hand, has 1,000,000 sides.
More advanced geometry deals with three-dimensional spaces such as the cylinder and rectangular prism.
Perimeter is the total distance around a shape. Perimeter can be compared to a fence around a yard. Perimeter is calculated differently for every shape. Calculating the perimeter for an object is relatively easy: simply add the lengths of the sides together. For more complicated geometry problems, the lengths of certain sides may be left out. If this is the case, assumptions should be made about the other sides. For instance, if a side of a rectangle is left out, the mathematician can simply use the length of the opposite side. This is because opposite sides of rectangles are equal in length.
Area is another fundamental part of geometry. It is the measurement of surface space a two-dimensional object covers. Area is expressed using square units and is always found using multiplication. Formulas vary for an object's area. Rectangles have the simplest formula for area.
Area is found by simply multiplying the length by the width. The area of triangles is slightly harder to find. The formula for the area of a triangle is 0.5 x b x w, where "b" represents the base of the triangle and "w" represents its width.
Volume is similar to area in that it measures the space an object occupies. Volume, as opposed to area, relates to three-dimensional objects, however. Volume equations differ greatly. The simplest volume to find is that of the rectangular prism: simply find the area of the base and then multiply by the height.
The volume of a rectangular prism can be calculated by using the formula V = l x w x h, where "V" is the volume of the prism, "l" is the length of the base, "w" is the width of the base and "h" is the height of the prism. Another common three-dimensional object is the cylinder. Its volume is found using the formula V = (pi x d^2 x h)/4, where "V" represents volume, "pi" represents the constant pi, which is approximately 3.14, "d" is diameter and "h" is the height of the cylinder. Volume is measured in cubic units.