The tangent of an angle is the ratio of the
y -value to the
x -value of the corresponding point on the unit circle.
The secant, cotangent, and cosecant are all reciprocals of other functions. The secant is the reciprocal of the cosine function, the cotangent is the reciprocal of the tangent function, and the cosecant is the reciprocal of the sine function.
The six trigonometric functions can be found from a point on the unit circle. See
[link] .
Trigonometric functions can also be found from an angle. See
[link] .
Trigonometric functions of angles outside the first quadrant can be determined using reference angles. See
[link] .
A function is said to be even if
and odd if
Cosine and secant are even; sine, tangent, cosecant, and cotangent are odd.
Even and odd properties can be used to evaluate trigonometric functions. See
[link] .
The Pythagorean Identity makes it possible to find a cosine from a sine or a sine from a cosine.
Identities can be used to evaluate trigonometric functions. See
[link] and
[link] .
Fundamental identities such as the Pythagorean Identity can be manipulated algebraically to produce new identities. See
[link] .
The trigonometric functions repeat at regular intervals.
The period
of a repeating function
is the smallest interval such that
for any value of
The values of trigonometric functions of special angles can be found by mathematical analysis.
To evaluate trigonometric functions of other angles, we can use a calculator or computer software. See
[link] .
Section exercises
Verbal
On an interval of
can the sine and cosine values of a radian measure ever be equal? If so, where?
Yes, when the reference angle is
and the terminal side of the angle is in quadrants I and III. Thus, at
the sine and cosine values are equal.
Abiotic factors are non living components of ecosystem.These include physical and chemical elements like temperature,light,water,soil,air quality and oxygen etc
