Sine
The sine is by definition the second coordinate on the unit circle.
Explanation
The cosine of θ is by definition, the first coordinate of the point P (x, y) on the unit circle, and the sine of θ is the second coordinate.
In this way obtuse angles can have a sine or cosine. The name cosine comes from complementary sine. There are only two functions f (x) and g (x) that satisfy the conditions
and these are the sine and the cosine, as
Example 1
In the figure you can see that sin (0) = sin (π) = sin (2π) = 0 and sin (90°) = sin (½π) = 1.
HistoryThe abbreviation sin was first used by the French mathematician Albert Girard (1595 - 1632). |