DICT.TW Dictionary Taiwan
Secant, n.
1. Geom. A line that cuts another; especially, a straight line cutting a curve in two or more points.
2. Trig. A right line drawn from the center of a circle through one end of a circular arc, and terminated by a tangent drawn from the other end; the number expressing the ratio of this line to the radius of the circle. See Trigonometrical function, under Function.
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Sine n. Trig. (a) The length of a perpendicular drawn from one extremity of an arc of a circle to the diameter drawn through the other extremity. (b) The perpendicular itself. See Sine of angle, below.
Artificial sines, logarithms of the natural sines, or logarithmic sines.
Curve of sines. See Sinusoid.
Natural sines, the decimals expressing the values of the sines, the radius being unity.
Sine of an angle, in a circle whose radius is unity, the sine of the arc that measures the angle; in a right-angled triangle, the side opposite the given angle divided by the hypotenuse. See Trigonometrical function, under Function.
Versed sine, that part of the diameter between the sine and the arc.
Tan·gent n. Geom. A tangent line curve, or surface; specifically, that portion of the straight line tangent to a curve that is between the point of tangency and a given line, the given line being, for example, the axis of abscissas, or a radius of a circle produced. See Trigonometrical function, under Function.
Artificial tangent, or Logarithmic tangent, the logarithm of the natural tangent of an arc.
Natural tangent, a decimal expressing the length of the tangent of an arc, the radius being reckoned unity.
Tangent galvanometer Elec., a form of galvanometer having a circular coil and a short needle, in which the tangent of the angle of deflection of the needle is proportional to the strength of the current.
Tangent of an angle, the natural tangent of the arc subtending or measuring the angle.
Tangent of an arc, a right line, as ta, touching the arc of a circle at one extremity a, and terminated by a line ct, passing from the center through the other extremity o.
Trig·o·no·met·ric Trig·o·no·met·ric·al Of or pertaining to trigonometry; performed by the rules of trigonometry.
--Trig*o*no*met*ric*al*ly, adv.
Trigonometrical curve, a curve one of whose coordinates is a trigonometric function of the other.
Trigonometrical function. See under Function.
Trigonometrical lines, lines which are employed in solving the different cases of plane and spherical trigonometry, as sines, tangents, secants, and the like. These lines, or the lengths of them, are trigonometrical functions of the arcs and angles to which they belong.
Trigonometrical survey. See under Survey.
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Func·tion n.
1. The act of executing or performing any duty, office, or calling; performance. “In the function of his public calling.”
2. Physiol. The appropriate action of any special organ or part of an animal or vegetable organism; as, the function of the heart or the limbs; the function of leaves, sap, roots, etc.; life is the sum of the functions of the various organs and parts of the body.
3. The natural or assigned action of any power or faculty, as of the soul, or of the intellect; the exertion of an energy of some determinate kind.
As the mind opens, and its functions spread. --Pope.
4. The course of action which peculiarly pertains to any public officer in church or state; the activity appropriate to any business or profession.
Tradesmen . . . going about their functions. --Shak.
The malady which made him incapable of performing his
regal functions. --Macaulay.
5. Math. A quantity so connected with another quantity, that if any alteration be made in the latter there will be a consequent alteration in the former. Each quantity is said to be a function of the other. Thus, the circumference of a circle is a function of the diameter. If x be a symbol to which different numerical values can be assigned, such expressions as x², 3ₓ, Log. x, and Sin. x, are all functions of x.
6. Eccl. A religious ceremony, esp. one particularly impressive and elaborate.
Every solemn ‘function' performed with the requirements of the liturgy. --Card. Wiseman.
7. A public or social ceremony or gathering; a festivity or entertainment, esp. one somewhat formal.
This function, which is our chief social event. --W. D. Howells.
Algebraic function, a quantity whose connection with the variable is expressed by an equation that involves only the algebraic operations of addition, subtraction, multiplication, division, raising to a given power, and extracting a given root; -- opposed to transcendental function.
Arbitrary function. See under Arbitrary.
Calculus of functions. See under Calculus.
Carnot's function Thermo-dynamics, a relation between the amount of heat given off by a source of heat, and the work which can be done by it. It is approximately equal to the mechanical equivalent of the thermal unit divided by the number expressing the temperature in degrees of the air thermometer, reckoned from its zero of expansion.
Circular functions. See Inverse trigonometrical functions (below). -- Continuous function, a quantity that has no interruption in the continuity of its real values, as the variable changes between any specified limits.
Discontinuous function. See under Discontinuous.
Elliptic functions, a large and important class of functions, so called because one of the forms expresses the relation of the arc of an ellipse to the straight lines connected therewith.
Explicit function, a quantity directly expressed in terms of the independently varying quantity; thus, in the equations y = 6x², y = 10 -x³, the quantity y is an explicit function of x.
Implicit function, a quantity whose relation to the variable is expressed indirectly by an equation; thus, y in the equation x² + y² = 100 is an implicit function of x.
Inverse trigonometrical functions, or Circular functions, the lengths of arcs relative to the sines, tangents, etc. Thus, AB is the arc whose sine is BD, and (if the length of BD is x) is written
One-valued function, a quantity that has one, and only one, value for each value of the variable.
Transcendental functions, a quantity whose connection with the variable cannot be expressed by algebraic operations; thus, y in the equation y = 10ₓ is a transcendental function of x. See Algebraic function (above).
Trigonometrical function, a quantity whose relation to the variable is the same as that of a certain straight line drawn in a circle whose radius is unity, to the length of a corresponding are of the circle. Let AB be an arc in a circle, whose radius OA is unity let AC be a quadrant, and let OC, DB, and AF be drawnpependicular to OA, and EB and CG parallel to OA, and let OB be produced to G and F. E Then BD is the sine of the arc AB; OD or EB is the cosine, AF is the tangent, CG is the cotangent, OF is the secant OG is the cosecant, AD is the versed sine, and CE is the coversed sine of the are AB. If the length of AB be represented by x (OA being unity) then the lengths of Functions. these lines (OA being unity) are the trigonometrical functions of x, and are written
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