# Mathematical Dictionary - Letter P (continued)

EXCHANGES - Arrange a set of elements in all possible ways such that only the order of these elements is a form of distinction. Example: word permutations use: use, uos, osu, ous, suo, sou. If the set consists of no elements, the permutations obtained are n! (factorial).

PERPENDICULAR - Two lines are perpendicular when intersecting at right angles.

WEIGHT - See pasta.

PI ( )- Constant (irrational) value used to calculate circumference, area and volume of circumference-related figures and solids. PICTOGRAM - A graph in which data is represented by drawings or images.

PYRAMID - A polyhedron that is based on a polygon and as sides, triangles that meet at a common point. PLAN - Surface where there are two and only two dimensions. It can be defined by: 3 non-collinear points (one line and point outside it) by two non-overlapping lines.

PLURIVOCA - Matching multiple objects with multiple objects. Four $5 candies correspond to five$ 4 candies, at least in price.

INCH - English measure of length, equivalent to 2.54 cm of the decimal metric system.

POLYHEDRON - A solid limited by polygons.

STAR POLYEDER - It is a polyhedron where on each face there is a pyramid.

POLYGONAL - Data presentation form where each element or class is linked to the next by a line segment. Or where the bars are replaced by line segments.

POLYGON - A closed flat region bounded by straight segments.

CIRCUMSCRIPTED POLYGON - A polygon is circumscribed to a circle if all its sides are tangent to the circle. In this case it can be said that the circumference is inscribed on the polygon. CONCONAVO POLYGON - When joining any of its two points by a segment, it does not pass outside the polygon. Any of its internal angles is greater than 180º.

INSCRIPTED POLYGON - A polygon is inscribed to a circle if all its vertices are points of the circle. In this case we can say that the circumference is circumscribed to the polygon. A - B - C - D - E - F - G - H - I / J / K - L - M - N - O - P - Q - R - S - T - U / V - X / Z