Trigonometric Formulas:
Below are the list of all trigonometric functions formulas;
Basic Formulas:
OR
\ csc \ left( \theta\right)\ = \ \ frac1 {\ sin\ left( \theta\right)}
=====
\ cos \ left( \theta\right) \ = \ \ frac1 {\ sec( \theta)}\
OR
sec \ left( \theta\right) \ = \ \ frac1 {\ cos\ left( \theta\right)}
=====
\ tan\ left( \theta\right) \ = \ \frac {\ sin\ left( \theta\right)}{\ cos\ left( \theta\right)}\
OR
\ tan\ left( \theta\right) \ = \ \frac1 {\ cot\ left( \theta\right)}
=====
\ cot\ left( \theta\right)\ = \ \ frac {\ cos\ left( \theta\right)}{\ sin \ left( \theta\right)}
OR
\ cot \ left( \theta\right) \ = \ \ frac1 {\ tan\ left( \theta\right)}
=====
\ sin^2\ left( \theta\right) \ + \ \ cos^2 \ left( \theta\right)\ = \ 1 \
OR
\ sin^2\ left( \theta\right) \ = \ 1 \ - \ \ cos^2 \ left( \theta\right)
OR
\ cos^2 \ left( \theta\right) \ = \ 1 \ - \ \ sin^2 \ left( \theta\right)
=====
1 \ + \ \ tan^2 \ left( \theta\right) \ = \ \ sec^2 \ left( \theta\right)
OR
\ tan^2 \ left( \theta\right) \ = \ \ sec^2 \ left(\theta\right) \ - \ 1
=====
1 \ + \ \cot^2\ left( \theta\right) \ = \ \ csc^2 \ left(\theta\right)
OR
\ cot^2 \ left( \theta\right) \ = \ \ csc^2 \ left( \theta\right) \ - \ 1
=====
\ csc \ left( \theta\right)\ = \ \ frac1 {\ sin\ left( \theta\right)}
=====
sec \ left( \theta\right) \ = \ \ frac1 {\ cos\ left( \theta\right)}
=====
=====
NEGATIVE(-ve) ANGLE FORMULAS:
\ sin \ left( -\theta\right) \ =\ - \ sin\ left( \theta\right)
\ cos \ left( -\theta\right) \ = \ \ cos\ left( \theta\right)
\ tan \ left( -\theta\right) \ = \ - \ tan\ left( \theta\right)
\ cot \ left( -\theta\right) \ = \ - \ cot\ left( \theta\right)
\ sec \ left( -\theta\right) \ =\ \ sec\ left( \theta\right)
\ csc \ left( -\theta\right) \ = \ - \ csc\ left( \theta\right)
\ sin \ left( -\theta\right) \ =\ - \ sin\ left( \theta\right)
\ cos \ left( -\theta\right) \ = \ \ cos\ left( \theta\right)
\ tan \ left( -\theta\right) \ = \ - \ tan\ left( \theta\right)
\ cot \ left( -\theta\right) \ = \ - \ cot\ left( \theta\right)
\ sec \ left( -\theta\right) \ =\ \ sec\ left( \theta\right)
\ csc \ left( -\theta\right) \ = \ - \ csc\ left( \theta\right)
\ cos \ left( -\theta\right) \ = \ \ cos\ left( \theta\right)
\ tan \ left( -\theta\right) \ = \ - \ tan\ left( \theta\right)
\ cot \ left( -\theta\right) \ = \ - \ cot\ left( \theta\right)
\ sec \ left( -\theta\right) \ =\ \ sec\ left( \theta\right)
\ csc \ left( -\theta\right) \ = \ - \ csc\ left( \theta\right)
DOUBLE ANGLE FORMULAS:
\ sin \ left( 2\theta\right) \ = \ 2 \ sin\ left( \theta\right) \ cos\ left( \theta\right)
OR
\ sin \ left( 2\theta\right)\ = \ \ frac { 2 \tan\left( \theta\right)}{ 1\ + \ \ tan^2\ left( \theta\right)}
=====
\ cos \ left( 2\theta\right) \ = \ \ cos^2\ left( \theta\right)\ -\ \ sin^2\ left( \theta\right)
OR
\ cos \ left( 2\theta\right) \ = \ 2 \ cos^2 \ left( \theta\right)\ - \ 1
OR
\ cos \ left( 2\theta\right) \ = \ 1\ - \ 2 \ sin^2\ left( \theta\right)
OR
\ cos \ left( 2\theta\right) \ = \ \ frac {1\ - \ \ tan^2\ left( \theta\right)}{1\ + \ \ tan^2\ left( \theta\right)}
= = = = =
\ tan \ left( 2\theta\right) \ = \ \ frac { 2 \ tan \ left( \theta\right)}{ 1-\ tan^2\ left( \theta\right)}
\ sin \ left( 2\theta\right) \ = \ 2 \ sin\ left( \theta\right) \ cos\ left( \theta\right)
OR
\ sin \ left( 2\theta\right)\ = \ \ frac { 2 \tan\left( \theta\right)}{ 1\ + \ \ tan^2\ left( \theta\right)}
=====
\ cos \ left( 2\theta\right) \ = \ \ cos^2\ left( \theta\right)\ -\ \ sin^2\ left( \theta\right)
OR
\ cos \ left( 2\theta\right) \ = \ 2 \ cos^2 \ left( \theta\right)\ - \ 1
OR
\ cos \ left( 2\theta\right) \ = \ 1\ - \ 2 \ sin^2\ left( \theta\right)
OR
\ cos \ left( 2\theta\right) \ = \ \ frac {1\ - \ \ tan^2\ left( \theta\right)}{1\ + \ \ tan^2\ left( \theta\right)}
= = = = =
\ tan \ left( 2\theta\right) \ = \ \ frac { 2 \ tan \ left( \theta\right)}{ 1-\ tan^2\ left( \theta\right)}
HALF ANGLE FORMULAS:
\ sin \ left( \ frac \alpha2\ right) \ = \ \ pm \ sqrt{ \ frac { 1- \ cos\ left( \ alpha \ right)} 2}
\ cos \ left( \ frac \alpha2\ right) \ = \ \ pm \ sqrt{ \ frac { 1+ \ cos\ left( \ alpha \ right)} 2}
\
tan \ left( \ frac \alpha2\ right) \ = \ pm \ sqrt{ \ frac{1 - \ cos\
left( \ alpha \ right)} {1 + \ cos\ left( \ alpha \ right)}}
\ sin \ left( \ frac \alpha2\ right) \ = \ \ pm \ sqrt{ \ frac { 1- \ cos\ left( \ alpha \ right)} 2}
\ cos \ left( \ frac \alpha2\ right) \ = \ \ pm \ sqrt{ \ frac { 1+ \ cos\ left( \ alpha \ right)} 2}
\
tan \ left( \ frac \alpha2\ right) \ = \ pm \ sqrt{ \ frac{1 - \ cos\
left( \ alpha \ right)} {1 + \ cos\ left( \ alpha \ right)}}
FUNDAMENTAL LAWS:
\ sin \ left( \ alpha + \ beta \ right) = \ sin\ left( \ alpha \ right)
\ cos\ left( \ beta \ right) + \ cos\ left( \ alpha \ right)\ sin\
left(\ beta \ right)
\ sin\ left( \ alpha - \ beta \ right) = \ sin\ left( \ alpha \ right) \
cos\ left( \ beta \ right) - \ cos\ left( \ alpha \ right)\ sin\ left(\
beta \ right)
\ cos\ left( \ alpha + \ beta \ right) = \ cos\ left( \ alpha \ right) \
cos\ left( \ beta \ right) - \ sin\ left( \ alpha \ right)\ sin\ left(\
beta \ right)
\ cos\ left( \ alpha - \ beta \ right) = \ cos\ left( \ alpha \ right) \
cos\ left( \ beta \ right) + \ sin\ left( \ alpha \ right)\ sin\ left(\
beta \ right)
\ tan\ left( \ alpha + \ beta \ right) = \ frac { \ tan \ left( \
alpha \ right) + \ tan\ left( \ beta \ right) } {1- \ tan\ left( \ alpha
\ right) \ tan \ left( \ beta \ right) }
\
tan\ left( \ alpha -\ beta \ right) = \ frac { \ tan \ left( \ alpha \
right) -\ tan \ left( \ beta \ right) } {1 + \ tan\ left( \ alpha \
right) \ tan \ left( \ beta \ right) }
\
cot \ left( \ alpha + \ beta \ right) = \ frac { \ cot \ left( \ alpha \
right) \ cot\ left( \ beta \ right) - 1} { \ cot\ left( \ alpha \
right) + \ cot \ left( \ beta \ right)}
\
cot \ left( \ alpha -\ beta \ right) = \ frac { \ cot \ left( \ alpha
\right) \ cot\ left( \ beta \ right) + 1} { \ cot\ left( \ beta \ right)
- \ cot \ left( \ alpha \ right)}
PRODUCT TO SUM FORMULAS:
\ sin \ left( \ alpha \ right) \ \ cos \ left( \ beta \ right) = \
frac1\2 \ left[ \ sin \ left( \ alpha + \ beta \ right) + \ sin \ left( \
alpha - \ beta \ right) \ right]
\ cos \ left( \ alpha \ right) \ \ sin \ left( \ beta \ right) = \
frac1\2 \ left[ \ sin \ left( \ alpha + \ beta \ right) - \ sin \ left( \
alpha - \ beta \ right) \ right]
\ cos \ left( \ alpha \ right) \ \ cos \ left( \ beta \ right) = \
frac1\2 \ left[ \ cos \ left( \ alpha + \ beta \ right) + \ cos \ left( \
alpha - \ beta \ right) \ right]
\ sin \ left( \ alpha \ right) \ \ sin \ left( \ beta \ right) = - \
frac1\2 \ left[ \ cos \ left( \ alpha + \ beta \ right) - \ cos \ left( \
alpha - \ beta \ right) \ right]
\ sin \ left( \ alpha \ right) \ \ cos \ left( \ beta \ right) = \
frac1\2 \ left[ \ sin \ left( \ alpha + \ beta \ right) + \ sin \ left( \
alpha - \ beta \ right) \ right]
\ cos \ left( \ alpha \ right) \ \ sin \ left( \ beta \ right) = \
frac1\2 \ left[ \ sin \ left( \ alpha + \ beta \ right) - \ sin \ left( \
alpha - \ beta \ right) \ right]
\ cos \ left( \ alpha \ right) \ \ cos \ left( \ beta \ right) = \
frac1\2 \ left[ \ cos \ left( \ alpha + \ beta \ right) + \ cos \ left( \
alpha - \ beta \ right) \ right]
\ sin \ left( \ alpha \ right) \ \ sin \ left( \ beta \ right) = - \
frac1\2 \ left[ \ cos \ left( \ alpha + \ beta \ right) - \ cos \ left( \
alpha - \ beta \ right) \ right]
SUM TO PRODUCT FORMULAS:
\
sin \ left( \ upsilon \ right) + \ sin \ left( \ nu \ right) = 2 \ sin \
left( \ frac { \ upsilon + \ nu} 2 \ right) \ cos \ left( \ frac { \
upsilon - \ nu} 2 \ right)
\ sin \ left( \
upsilon \ right) -\ sin \ left( \ nu \ right) = 2 \ cos \ left( \ frac {
\ upsilon + \ nu} 2 \ right) \ sin \ left( \ frac { \ upsilon - \ nu} 2
\ right)
\ cos \ left( \ upsilon \ right) +
\ cos \ left( \ nu \ right) = 2 \ cos \ left( \ frac { \ upsilon + \
nu} 2 \ right) \ cos \ left( \ frac { \ upsilon - \ nu} 2 \ right)
\
cos \ left( \ upsilon \ right) -\ cos \ left( \ nu \ right) = - 2 \ sin
\ left( \ frac { \ upsilon + \ nu} 2 \ right) \ sin \ left( \ frac { \
upsilon - \ nu} 2 \ right)
\
sin \ left( \ upsilon \ right) + \ sin \ left( \ nu \ right) = 2 \ sin \
left( \ frac { \ upsilon + \ nu} 2 \ right) \ cos \ left( \ frac { \
upsilon - \ nu} 2 \ right)
\ sin \ left( \
upsilon \ right) -\ sin \ left( \ nu \ right) = 2 \ cos \ left( \ frac {
\ upsilon + \ nu} 2 \ right) \ sin \ left( \ frac { \ upsilon - \ nu} 2
\ right)
\ cos \ left( \ upsilon \ right) +
\ cos \ left( \ nu \ right) = 2 \ cos \ left( \ frac { \ upsilon + \
nu} 2 \ right) \ cos \ left( \ frac { \ upsilon - \ nu} 2 \ right)
\
cos \ left( \ upsilon \ right) -\ cos \ left( \ nu \ right) = - 2 \ sin
\ left( \ frac { \ upsilon + \ nu} 2 \ right) \ sin \ left( \ frac { \
upsilon - \ nu} 2 \ right)
LAW OF SINE:
\
frac { \ sin \ left( \ alpha \ right) } a = \ frac{ \ sin \ left( \
beta \ right) } b = \ frac{ \ sin \ left( \ gamma \ right) } c
OR
\
frac a { \ sin \ left( \ alpha \ right) } = \ frac b { \sin \ left( \
beta \ right) } = \ frac c { \ sin \ left( \ gamma \ right) }
OR
a
\ : \ b \ : \ c \ = \ \ sin\ left( \ alpha \ right) \ : \ \ sin \
left( \ beta \ right) \ : \ \ sin \ left( \ gamma \ right)
\
frac { \ sin \ left( \ alpha \ right) } a = \ frac{ \ sin \ left( \
beta \ right) } b = \ frac{ \ sin \ left( \ gamma \ right) } c
OR
\
frac a { \ sin \ left( \ alpha \ right) } = \ frac b { \sin \ left( \
beta \ right) } = \ frac c { \ sin \ left( \ gamma \ right) }
OR
a
\ : \ b \ : \ c \ = \ \ sin\ left( \ alpha \ right) \ : \ \ sin \
left( \ beta \ right) \ : \ \ sin \ left( \ gamma \ right)
LAW OF COSINE:
\ cos \ left( \ alpha \ right) = \ frac { b^2 + c^2 - a^2} { 2bc }
OR
a^2 = b^2 + c^2 -2bc \ cos \ left( \ alpha \ right)
=====
\ cos \ left( \ beta \ right) = \ frac { a^2 + c^2 - b^2} { 2ac }
OR
b^2 = a^2 + c^2 -2ac \ cos \ left( \ beta \ right)
=====
\ cos \ left( \ gamma \ right) = \ frac { a^2 + b^2 - c^2} { 2ab }
OR
c^2 = a^2 + b^2 -2ab \ cos \ left( \ gamma \ right)
\ cos \ left( \ alpha \ right) = \ frac { b^2 + c^2 - a^2} { 2bc }
OR
a^2 = b^2 + c^2 -2bc \ cos \ left( \ alpha \ right)
=====
\ cos \ left( \ beta \ right) = \ frac { a^2 + c^2 - b^2} { 2ac }
OR
b^2 = a^2 + c^2 -2ac \ cos \ left( \ beta \ right)
=====
\ cos \ left( \ gamma \ right) = \ frac { a^2 + b^2 - c^2} { 2ab }
OR
c^2 = a^2 + b^2 -2ab \ cos \ left( \ gamma \ right)
HALF ANGLE FORMULAS:
\ sin \ left( \ frac \alpha2\ right) \ = \ sqrt { \ frac { (s-b) \ (s-c) } { bc } }
\ sin \ left( \ frac \beta2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-c) } { ac } }
\ sin \ left( \ frac \gamma2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-b) } { ab } }
\ cos \ left( \ frac \alpha2\ right) \ = \ sqrt { \ frac { s (s-a) } { bc } }
\ cos \ left( \ frac \beta2\ right) \ = \ sqrt { \ frac { s (s-b) } { ac } }
\ cos \ left( \ frac \gamma2\ right) \ = \ sqrt { \ frac { s (s-c) } { ab } }
\ tan \ left( \ frac \alpha2\ right) \ = \ sqrt { \ frac { (s-b) \ (s-c) } { s (s-a) } }
\ tan \ left( \ frac \beta2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-c) } { s (s-b) } }
\ tan \ left( \ frac \gamma2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-b) } { s (s-c) } }
\ sin \ left( \ frac \alpha2\ right) \ = \ sqrt { \ frac { (s-b) \ (s-c) } { bc } }
\ sin \ left( \ frac \beta2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-c) } { ac } }
\ sin \ left( \ frac \gamma2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-b) } { ab } }
\ cos \ left( \ frac \alpha2\ right) \ = \ sqrt { \ frac { s (s-a) } { bc } }
\ cos \ left( \ frac \beta2\ right) \ = \ sqrt { \ frac { s (s-b) } { ac } }
\ cos \ left( \ frac \gamma2\ right) \ = \ sqrt { \ frac { s (s-c) } { ab } }
\ tan \ left( \ frac \alpha2\ right) \ = \ sqrt { \ frac { (s-b) \ (s-c) } { s (s-a) } }
\ tan \ left( \ frac \beta2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-c) } { s (s-b) } }
\ tan \ left( \ frac \gamma2\ right) \ = \ sqrt { \ frac { (s-a) \ (s-b) } { s (s-c) } }
AREA OF A TRIANGLE:
\ triangle = Area
\ triangle = Area
3 SIDES GIVEN:
\ triangle = \ sqrt { s (s-a) (s-b) (s-c) }
s = \ frac { a + b + c } 2
\ triangle = \ sqrt { s (s-a) (s-b) (s-c) }
s = \ frac { a + b + c } 2
2 SIDES INCLUDED ANGLE GIVEN:
\ triangle = \ frac { bc \ sin \ left( \ alpha \ right) } 2
\ triangle = \ frac { ac \ sin \ left( \ beta \ right) } 2
\ triangle = \ frac { ab \ sin \ left( \ gamma \ right) } 2
\ triangle = \ frac { bc \ sin \ left( \ alpha \ right) } 2
\ triangle = \ frac { ac \ sin \ left( \ beta \ right) } 2
\ triangle = \ frac { ab \ sin \ left( \ gamma \ right) } 2
1 SIDES INCLUDED 2 ANGLES GIVEN:
\
triangle = \ frac { a^2 \ sin \ left( \ beta \ right) \ sin \ left( \
gamma \ right) } { 2 \ sin \ left( \ alpha \ right) }
\
triangle = \ frac { b^2 \ sin \ left( \ alpha \ right) \ sin \ left( \
gamma \ right) } { 2 \ sin \ left( \ beta \ right) }
\
triangle = \ frac { c^2 \ sin \ left( \ alpha \ right) \ sin \ left( \
beta \ right) } { 2 \ sin \ left( \ gamma \ right) }
\
triangle = \ frac { a^2 \ sin \ left( \ beta \ right) \ sin \ left( \
gamma \ right) } { 2 \ sin \ left( \ alpha \ right) }
\
triangle = \ frac { b^2 \ sin \ left( \ alpha \ right) \ sin \ left( \
gamma \ right) } { 2 \ sin \ left( \ beta \ right) }
\
triangle = \ frac { c^2 \ sin \ left( \ alpha \ right) \ sin \ left( \
beta \ right) } { 2 \ sin \ left( \ gamma \ right) }
CIRCUM-RADIUS R IN TERMS OF THE MEASURE OF A THREE SIDES OF A TRIANGLE:
R \ = \ frac{ \ abc } { 4\triangle}
R \ = \ frac{ \ abc } { 4\triangle}
THE IN-RADIUS OF A TRIANGLE:
r = \ frac \triangle s
r = \ frac \triangle s