Trig Identities

Pythagorean Identities

sin²∅ + cos²∅ = 1

Pythagorean Identities

tan²∅ + 1 = sec²∅

Pythagorean Identities

cot²∅ + 1 = csc²∅

Reciprocal Identities: cot∅

1/(tan∅)

reciprocal identities: tan∅

1/(cot∅)

reciprocal identities: sin∅

1/(csc∅)

reciprocal identities: csc∅

1/(sin∅)

reciprocal identities: cos∅

1/(sec∅)

reciprocal identities: sec∅

1/(cos∅)

even function: cos∅/sec∅

cos(∅)=cos(-∅)

sec(∅)=sec(-∅)

odd function: tan∅/cot∅

-tan(∅)=tan(-∅)

-cot(∅)=cot(-∅)

odd function: sin∅/csc∅

sin(-∅)=-sin(∅)

csc(-∅)=-csc(∅)

tan(∅)

(sin∅)/(cos∅)

cot∅

(cos∅)/(sin∅)

sin(2∅)

2sin∅cos∅

cos(2∅)

cos^2(∅) - sin^2(∅)

cos(2∅)

2cos^2(∅) - 1

cos(2∅)

1 - 2sin^2(∅)

tan(2∅)

(2tan∅)/(1 - tan^2∅)

sin(x+y)

sinxcosy+cosxsiny

cos(x+y)

cosxcosy-sinxsiny

sin(x-y)

sinxcosy-cosxsiny

cos(x-y)

cosxcosy+sinxsiny

tan(x+y)

(tan x + tan y)/(1 - tan x × tan y)

tan(x-y)

(tan x- tan y)/(1 + tan x × tan y)

tan (x/2)

(1 - cos x)/sin x

sin (x/2)

+- square root((1 - cos x)/2)

cos (x/2)

+- square root ((1 + cos x)/2)