Pythagorean Identities, Sum and Difference Identities, Double Angle Identities
cos^2 x + sin^2 x=
1
1 - sin^2 x=
cos^2 x
( 1- sin x)(1+ sin x)
cos^2 x
1 - cos^2 x=
sin ^2 x
(1- cos x)(1+cos x)
sin^2 x
1 + tan^2 x=
sec^2 x
sec^2 x- tan^2 x=
1
(sec x - tan x)(sec x + tan x)=
1
tan^2 x-sec^2 x=
-1
(tan x- sec x)(tan x + sec x)=
-1
1 + cot^2 x =
csc^2 x
csc^2 x - cot^2 x=
1
(Csc x - cot x)(csc x+ cot x)=
1
cot^2 x - csc^2 x=
-1
(cot x- csc x)(cot x+csc x)=
-1
sin(A+B)=
(sin A)(cos B) + (sin B)(cos A)
sin(A-B)
(sin A)(cosB)-(Sin B)(Cos A)
cos(A+B)
(cos A)(cos B)- (sinA)(sinB)
cos(A-B)
(cos A)(cos B) + (sin A)(Sin B)
tan(A-B)
tan A - tan B/1+ (tan A)(tan B)t
tan(A+B)
tan A + tan B/ 1-(tan A)(tan B)
sin(2x)
2(sin x)(cos x)
cos(2x)
cos^2 x- sin^2 x
cos(2x)
2 cos^2 x-1
cos(2x)
1-2(sin^2 x)
tan(2x)
2(tan x)/1-tan^2 x