Principal Trigonometric Identities
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sin(-x)=
-sinx
tan(-x)=
-tanx
sin2x+cos2x=
1
sec(x)=
1/cosx
csc(x)=
1/sinx
cot(x)=
1/tanx
sin(2x) =
2sin(x)cos(x)
tan(2x) =
[2 tan(x)] / [1 - tan^2(x)]
tan(a + b) =
[tan(a) + tan(b)] / [1 - tan(a)tan(b)]
tan(a - b) =
[tan(a) - tan(b)] / [1 + tan(a)tan(b)]
cos(α - β) =
cos(α)cos(β) + sin(α)sin(β)
cos(α + β) =
cos(α)cos(β) - sin(α)sin(β)
cos(2x) =
cos2(x) - sin2(x)
cos(-x)=
cosx
cot(x)=
cosx/sinx
cot2x+1=
csc2x
tan2x+1=
sec2x
sin(α + β) =
sin(α)cos(β) + cos(α)sin(β)
sin(α - β) =
sin(α)cos(β) - cos(α)sin(β)
tan(x)=
sinx/cosx
