Half Angle Calculator




The half angle calculator helps you find the exact values of all trigonometric identities of the half-angle such as sin, cos, and tan.

Enter the θ angle in degrees and press the button to convert it into radian. You will be able to see the Sin(θ/2), Cos(θ/2), and Tan(θ/2) of the half angle.

You can also click the show steps button to see how these values were calculated.

  • Half angle formula of sin: sin A/2 = ±√[(1 – cos A) / 2]
  • Half angle formula of cos: cos A/2 = ±√[(1 + cos A) / 2]
  • Half angle formula of tan: tan A/2 = ±√[1 – cos A] / 1 + cos A sin A / (1 + cos A) (or) (1 – cos A) / sin A.
half angle Calculator and formula

You might be interested in finding the octagon vertices or polar coordinates.


  • Double‐Angle and Half‐Angle Identities. (n.d.). Double‐Angle and Half‐Angle Identities. https://www.cliffsnotes.com/study-guides/trigonometry/trigonometric-identities/double-angle-and-half-angle-identities
  • https://www2.clarku.edu/faculty/djoyce/trig/identities.html. (n.d.). https://www2.clarku.edu/faculty/djoyce/trig/identities.html
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