Trigonometry

The sine function and the cosine function graphs and relations
Trigonometric functions and inverse trigonometric functions or arc-functions
Trigonometric functions graphs and relations
Trigonometric (cyclometric) functions are defined as the ratios of the sides of a right triangle containing the angle equal to the argument of the function in radians.
Or more generally, for real arguments, trigonometric functions are defined in terms of the coordinates of the terminal point Q of the arc (or angle) of the unit circle with the initial point at P(1, 0).
 sin2x + cos2x = 1
-  The sine function  y = sin x is the y-coordinate of the terminal point of the arc x of the unit circle.
The graph of the sine function is the sine curve or sinusoid.
In a right-angled triangle the sine function is equal to the ratio of the length of the side opposite the given angle to the length of the hypotenuse.
-  The cosine function  y = cos x is the x-coordinate of the terminal point of the arc x of the unit circle.
The graph of the cosine function is the cosine curve or cosinusoid.
In a right-angled triangle the cosine function is equal to the ratio of the length of the side adjacent the given angle to the length of the hypotenuse.
Trigonometry contents B