Download SOME MATHEMATICAL TERMS

SOME MATHEMATICAL TERMS
As you know, mathematics is the science that deals with space and number.
Arithmetic, algebra, geometry, and trigonometry are branches of mathematics. In this text
you will learn the basic arithmetical and geometrical terms as they are used by the
English.
The numbers 1, 3, 5, 7, 9 are called odd numbers, and 0, 2, 4, 6, 8, are even
numbers. They are also termed cardinal numbers, and they tell us how many things or
persons are there in the set. Ordinal numbers, however, define the position of things in a
series. These are formed by adding th to the cardinal number, except for the first three,
which run as follows: 1st (first), 2nd (second), and 3rd (third). Note also the slight
modification in the ordinals: 5th (fifth), 9th (ninth), 12th (twelfth), and 20th (twentieth).
The four elementary rules, or arithmetical operations, are addition, subtraction,
multiplication, and division. The following expressions should be read like this:
10 + 3 = 13 ten plus (or and) three is (are) thirteen.
35 – 5 = 30 thirty-five minus (or less) five is thirty.
7 × 9 = 63
seven times (or multiplied by) nine is sixty-three.
40 : 8 = 5
forty divided by eight is five.
The results of the four operations in the above equations are called he sum (or
sum total), the remainder, the product, and the quotient, respectively.
The number 50386 or any other whole number is called an integer, and it contains
five digits. A digit is any numeral from 0 to 9. On the other hand the quantities 1/2 (one
half), 2/3 (two-thirds), 3/4 (three-fourths) are called vulgar fraction. They are also known
as proper fractions their numerators are smaller than their denominators. But if it is the
other way round, they are called improper fractions, e.g., 3/2 (three halves), 5/4 (fivefourths) etc. Fractions such as x/y and a/b should be read as x over y, and a over b. A
decimal fraction, however, is written and read in this manner: 2.7 (two point seven),
5.063 (five point nought six three), or .01 (point nought one).
You should also know how a number or mathematical expression is raised to a
certain power. We speak of the second, third, fourth, etc. power of a number. For
example, 42 is the second power of four, or simply, four squared; 53 is the third power of
five, or simply, five cubed. Similarly, a5 is a to the fifth power, x-5 is x to the power of
minus five. The small numbers (2, 3, 5, -5) are called indices and they indicate the power
to which a quantity is raised.
The root of a number, as you know, represents a completely reversed procedure.
Thus, the number 3 is the square root of 9 = √9, the cube root of 27 = 3√27, the fourth
root of 81 = 4√81, etc.
Geometry is that branch of mathematics which deals with the properties of lines,
angles, surfaces, and solids. While plane geometry is concerned with such plane figures
as triangles, squares, rectangles, circles, etc., solid geometry deals with solid figures, that
is those having length, breadth, and thickness.
The triangle is a plane figure bounded by three sides and having three angles,
whose total sum is 1800 (degrees). A triangle containing a right angle is called a rightangled triangle. An angle that has less than 900 is called an obtuse angle.
A square is a quadrilateral figure, all the four sides of which are equal. The area of
a rectangular figure is computed by multiplying the two adjacent sides. If one side is 5 m
(metres) long, and the other 6 m, the area will be 5m by 6m, which makes 30 m2 (square
metres).
You should also distinguish between straight lines (horizontal, vertical, and
slanting) and curved lines, or curves. The most common curves are the circle, ellipse,
parabola, and hyperbola. Some of the terms usually associated with the circle are: centre,
circumference, radius, diameter, sector, and arc.
The cube is a solid body with six equal square sides. The sphere is a solid figure
where every part of its surface is equidistant from the centre. The cone is a solid with a
circular base tapering to a point. The pyramid is a solid figure with a polygonal or square
base, whose sloping sides meet at an apex. The cylinder is a solid generated by a straight
line moving parallel to itself and describing any fixed curves, especially a circle.