Cofunction identity: tan(π/2 − θ) = cot θ
Tangent and cotangent are cofunctions: tan(π/2 − θ) = cot θ. The same complementary-angle relationship holds for every function-and-cofunction pair - sine/cosine, tangent/cotangent, secant/cosecant.
Related Cofunction identities
Common questions
What is the tan(π/2 − θ) = cot θ identity?
Tangent and cotangent are cofunctions: tan(π/2 − θ) = cot θ. The same complementary-angle relationship holds for every function-and-cofunction pair - sine/cosine, tangent/cotangent, secant/cosecant.
Which identities are related to tan(π/2 − θ) = cot θ?
tan(π/2 − θ) = cot θ belongs to the Cofunction group. The identities used alongside it most often are sin(π/2 − θ) = cos θ and cos(π/2 − θ) = sin θ.
Practise it
Reading a formula is not the same as recalling it under time pressure. The workspace drills Cofunction questions in the quiz, and the triangle solver shows a worked solution for any triangle you type in.
Or browse all 45 identities in the full reference, or read the trigonometry guides for the method behind them.