Trig identity calculator

Fundamental trig identities

Pythagorean: sin²x + cos²x = 1, 1 + tan²x = sec²x, 1 + cot²x = csc²x

Reciprocal: cscx = 1/sinx, secx = 1/cosx, cotx = 1/tanx

Quotient: tanx = sinx/cosx, cotx = cosx/sinx

Double angle

sin(2x) = 2sin(x)cos(x), cos(2x) = cos²x − sin²x = 2cos²x − 1 = 1 − 2sin²x

Sum/difference

sin(a±b) = sin(a)cos(b) ± cos(a)sin(b), cos(a±b) = cos(a)cos(b) ∓ sin(a)sin(b)