Cofunction Calculator

Your details

Switch between degrees (90 deg complement) and radians (pi/2 complement).
The angle whose cofunction you want. In degrees the complement is 90 - theta; in radians it is pi/2 - theta.
deg
For multiples of 30 deg and 45 deg the calculator shows the exact radical form (e.g. sqrt(3)/2).
Cofunction identity
sin(30 deg) = cos(60 deg)

The cofunction expression equal to your input.

Complementary angle60
Shared decimal value0.5
Exact value1/2
Shared value (decimal)0.5
Complementary angle60

sin(30 deg) shares its value with cos(60 deg).

  • Both expressions equal 0.5 (exact form: 1/2).
  • The word "co-" means complement. Cosine is literally the "complement's sine," cotangent is the "complement's tangent," and cosecant is the "complement's cosecant."
  • The identity holds for any angle, not just angles between 0 deg and 90 deg. For an obtuse angle the complement is negative and the identity still holds wherever both functions are defined.

Next stepSwap the function to see the reverse: if sin(30 deg) = cos(60 deg), then cos(60 deg) = sin(30 deg) by the same identity.

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