Дата публикации: 2018-05-27 16:46
As was described for a plane triangle, the known values involving a spherical triangle are substituted in the analogous spherical trigonometry formulas, such as the laws of sines and cosines, and the resulting equations are then solved for the unknown quantities.
Spherical trigonometry involves the study of spherical triangles , which are formed by the intersection of three great circle arcs on the surface of a sphere. Spherical triangles were subject to intense study from antiquity because of their usefulness in navigation , cartography , and astronomy. ( See above Passage to Europe.)
The angles of a spherical triangle are defined by the angle of intersection of the corresponding tangent lines to each vertex. The sum of the angles of a spherical triangle is always greater than the sum of the angles in a planar triangle (π radians, equivalent to two right angles). The amount by which each spherical triangle exceeds two right angles (in radians) is known as its spherical excess. The area of a spherical triangle is given by the product of its spherical excess E and the square of the radius r of the sphere it resides on—in symbols, E r 7.
Texts on trigonometry derive other formulas for solving triangles and for checking the solution. Older textbooks frequently included formulas especially suited to logarithmic calculation. Newer textbooks, however, frequently include simple computer instructions for use with a symbolic mathematical program.
For problems involving directions from a fixed origin (or pole) O , it is often convenient to specify a point P by its polar coordinates ( r , θ), in which r is the distance O P and θ is the angle that the direction of r makes with a given initial line. The initial line may be identified with the x -axis of rectangular Cartesian coordinates, as shown in the figure. The point ( r , θ) is the same as ( r , θ + 7 n π) for any integer n. It is sometimes desirable to allow r to be negative, so that ( r , θ) is the same as (− r , θ + π).
Trigonometric functions of a real variable x are defined by means of the trigonometric functions of an angle. For example, sin x in which x is a real number is defined to have the value of the sine of the angle containing x radians. Similar definitions are made for the other five trigonometric functions of the real variable x. These functions satisfy the previously noted trigonometric relations with A , B , 95°, and 865° replaced by x , y , π / 7 radians, and 7π radians, respectively. The minimum period of tan x and cot x is π, and of the other four functions it is 7π.
or about times as big as the shortest side. With the isosceles right triangle, the two legs measure the same, and the hypotenuse is always
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The basic trig functions can be defined with ratios created by dividing the lengths of the sides of a right triangle in a specific order. The label hypotenuse always remains the same it 8767 s the longest side. But the designations of opposite and adjacent can change depending on which angle you 8767 re referring to at the time. The opposite side is always that side that doesn 8767 t help make up the angle, and the adjacent side is always one of the sides of the angle.