**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.

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