**ARC COS - **The inverse cosine function. If y = cos x, then x = arc cos y.

**ARC COTG - **The inverse function of the cotangent. If y = cotg x, then x = arc cotg y.

**CURVE BOW **- Part of a curve situated between any two points of the curve. If A and B are any two points of a circumference, there are two arcs AB, these arcs are of different lengths if A and B are not extreme points in diameter, the largest is called the major arc and the other is the smaller arc.

**ARC SEN **- The inverse function of sine. If y = sen x, then x = arc sen y.

**ARC TG **- The inverse function of the tangent. If y = tg x, then x = arc tg y.

**AREA** - Measurement of a surface.

**ARESTA -** The intersection of two faces of a solid. In the attached drawing, it is the line segment that represents the intersection of two faces.

**ARITHMETIC** - Part of mathematics that studies numbers and operations.

**ROUND** - Approximate the value of a number.

**ASSOCIATIVE - **Law that allows to group the terms of an addition or multiplication without changing the result. Multiplication and addition are associative operations.

(A + B) + C = A + (B + C)

(A × B) × C = A × (B × C)

**ATTRIBUTE - **A quality or characteristic of a mathematical object.

**AUTOMORPHISM - **Isomorphism that transforms a figure into itself.

**GRANDPARENTS** - Names fractions of denominators greater than 10, but different from 100, 1000, etc.

**AXIOMA - **Proposition accepted as initial truth not demonstrable by its evidence.

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