Definitions of the Trigonometric Functions of an Acute Angle
We already know some properties of a right triangle.
Two angles are called complements of one another if, together, they equal a right triangle. In a right triangle, the two acute angles are complementary.
There's also a corelation between acute angles and sides of the right triangle.
Trigonometric Functions of Angle a
Side a is an opposite catheti, and side b is an adjacent catheti to angle a.
Sine function of angle a is defined as a qotient of opposite catheti and hypotenuse.
Cosine function of angle a is defined as a quotient of adjacent catheti and hypotenuse.
Tangent function of angle a is defined as a quotient of opposite catheti and adjacent catheti.
Cotangent function of angle a is defined as a quotient of adjacent catheti and opposite catheti.
Apart from these four functions, two more ratios can be defined:
Secant function of angle a is defined as a quotient of hypotenuse and opposite catheti.
Cosecant function of angle a is defined as a quotient of hypotenuse and adjacent catheti.
There are three pairs of trigonometric functions that we call cofunctions:
sine and cosine
tangent and cotangent
secant and cosecant
To find out main characteristic of trigonometric functions click here.
Table 1
