Double, Power reducing, Half, Product to Sum, Sum to Product Trigonometric Formulas

Cos(2x)

Cos(2x)

cos^2(x)-sin^2(x) 2cos^2(x)-1 1-2sin^2(x)

cos(A-B)

cosAcosB+sinAsinB

cos(A+B)

cosAcosB-sinAsinB

Cos(x) - cos(y)

-2sin[(x + y)/2]sin[(x - y)/2]

Cos(x) + cos(y)

2cos[(x + y)/2]cos[(x - y)/2]

Cos(x)cos(y)

1/2[cos(x-y)+cos(x+y)]

Cos(x/2)

±√[1+cos(x)/2]

Cos^2(x)

[1+cos(2x)]/2

cot(x)

cos(x)/sin(x)

cot^2(x)+1

csc^2(x)

Sin(2x)

2sin(x)cos(x)

sin(A-B)

sinAcosB-cosAsinB

sin(A+B)

sinAcosB+cosAsinB

Sin(x) - sin(y)

2sin[(x-y)/2]cos[(x+y)/2]

Sin(x) + sin(y)

2sin[(x + y)/2]cos[(x - y)/2]

Sin(x)cos(y)

1/2[sin(x+y)+sin(x-y)]

Sin(x)sin(y)

1/2[cos(x-y)-cos(x+y)]

Sin(x/2)

±√[1-cos(x)/2]

Sin^2(x)

[1-cos(2x)]/2

sin^2x+cos^2x

1

Tan(2x)

2tan(x)/[1-tan^2(x)]

tan(A-B)

(tanA - tanB) / (1 + tanAtanB)

tan(A+B)

(tanA + tanB)/(1 - tanAtanB)

tan(x)

sin(x)/cos(x)

Tan(x/2)

(1-cosx)/sinx sinx/(1+cosx) ±√((1-cosx)/(1+cosx))

Tan^2(x)

[1-cos(2x)]/[1+cos(2x)]

tan^2(x)+1

sec^2(x)