Cofunction Identities of
Trigonometry
The cofunction identities of trigonometry define
the relationship between sine (Sin), cosine (Cos), tangent (Tan), cotangent
(Cot), secant (Sec) and cosecant (Cosec). The value of a trigonometric function
at an angle equals the value of the cofunction of the complement.(A complement
is defined as two angles whose sum is 90°)
In Radians:
|
Sine and cosine are cofunctions and
complements
|
Sin
|
(
|
π
|
-
|
Ө
|
)
|
=
|
CosӨ
|
Cos
|
(
|
π
|
-
|
Ө
|
)
|
=
|
SinӨ
|
|
2
|
2
|
|||||||||||||||
|
Tangent and cotangent are cofunctions
and complements
|
Tan
|
(
|
π
|
-
|
Ө
|
)
|
=
|
CotӨ
|
Cot
|
(
|
π
|
-
|
Ө
|
)
|
=
|
TanӨ
|
|
2
|
2
|
|||||||||||||||
|
Secant and cosecant are cofunctions and
complements
|
Sec
|
(
|
π
|
-
|
Ө
|
)
|
=
|
CosecӨ
|
Cosec
|
(
|
π
|
-
|
Ө
|
)
|
=
|
SecӨ
|
|
2
|
2
|
In Degree:
Sine (Sin) and cosine (Cos)
are cofunctions and complements
|
sin(90° - Ө) = cos Ө
|
cos(90° - Ө) = sin Ө
|
Tangent (Tan) and cotangent(Cot)
are cofunctions and complements
|
tan(90° - Ө) = cot Ө
|
cot(90° - Ө) = tan Ө
|
Secant(Sec) and cosecant(Cosec)
are cofunctions and complements
|
sec(90° - Ө) = csc Ө
|
csc(90° - Ө) = sec Ө
|
If you find any doubts please free to ask them in the
comment section, We would be happy to reply with solution ASAP.