Sine and cosine are written using functional notation with the abbreviations sin and cos.
Often, if the argument is simple enough, the function value will … See more

Zero is the only real fixed point of the sine function; in other words the only intersection of the sine function and the identity function is $${\displaystyle \sin(0)=0}$$ See more

Sine and cosine are used to connect the real and imaginary parts of a complex number with its polar coordinates (r, φ):
$${\displaystyle z=r(\cos(\varphi )+i\sin(\varphi ))}$$ See more

Right-angled triangle definitions
To define the sine and cosine of an acute angle α, start with a right triangle that contains an angle of measure α; in the accompanying … See more

Exact identities (using radians):
These apply for all values of $${\displaystyle \theta }$$. See more

The law of sines states that for an arbitrary triangle with sides a, b, and c and angles opposite those sides A, B and C:
This is equivalent … See more

While the early study of trigonometry can be traced to antiquity, the trigonometric functions as they are in use today were developed in the … See more