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Since C = 2πr, the circumference of a unit circle is 2π. In mathematics, a unit circle is a circle of unit radius—that is, a radius of 1. [1] Frequently, especially in trigonometry, the unit circle is the circle of radius 1 centered at the origin (0, 0) in the Cartesian coordinate system in the Euclidean plane.
The Pythagorean triple (4,3,5) is associated to the rational point (4/5,3/5) on the unit circle. In mathematics, the rational points on the unit circle are those points (x, y) such that both x and y are rational numbers ("fractions") and satisfy x 2 + y 2 = 1. The set of such points turns out to be closely related to primitive Pythagorean triples.
The values of (), (), and are represented by the ordinates of points A, B, and D, respectively, while the values of (), (), and () are represented by the abscissas of points A, C and E, respectively.
All of the trigonometric functions of the angle θ (theta) can be constructed geometrically in terms of a unit circle centered at O. Sine function on unit circle (top) and its graph (bottom) In this illustration, the six trigonometric functions of an arbitrary angle θ are represented as Cartesian coordinates of points related to the unit circle.
Since the arithmetic mean is not always appropriate for angles, the following method can be used to obtain both a mean value and measure for the variance of the angles: Convert all angles to corresponding points on the unit circle , e.g., α {\displaystyle \alpha } to ( cos α , sin α ) {\displaystyle (\cos \alpha ,\sin \alpha )} .
Animation demonstrating how the sine function (in red) is graphed from the y-coordinate (red dot) of a point on the unit circle (in green), at an angle of θ. The cosine (in blue) is the x-coordinate. Using the unit circle definition has the advantage of drawing a graph of sine and cosine functions.
While trigonometric tables contain many approximate values, the exact values for certain angles can be expressed by a combination of arithmetic operations and square roots. The angles with trigonometric values that are expressible in this way are exactly those that can be constructed with a compass and straight edge , and the values are called ...
The Unit Circle is a circle of radius 1 unit, oftenly used to define the functions of trigonometry. In this diagram, individual points on the unit circle are labeled first with its coordinates (exact values), with the angle in degree angular measure, then with radian angular measure. Points in the lower hemisphere have both positive and ...