Double Angle Formula Calculator

Your details

Choose whether to enter the angle in degrees, radians, or as a multiple of pi.
The base angle theta. The calculator computes every double-angle identity for 2theta.
°
sin(2theta)
0.866025

Sine of the double angle, using sin(2theta) = 2 sin(theta) cos(theta)

cos(2theta)0.5
tan(2theta)1.732051
cos(2theta) = 2cos^2(theta) - 10.5
cos(2theta) = 1 - 2sin^2(theta)0.5
csc(2theta)1.154701
sec(2theta)2
cot(2theta)0.57735
2theta (degrees)60°
sin(2theta)0.866025
cos(2theta)0.5

sin(2theta) = 0.8660, cos(2theta) = 0.5000

  • sin(2theta) = 0.866025, cos(2theta) = 0.500000.
  • tan(2theta) = 1.732051.
  • sin^2(2theta) + cos^2(2theta) = 1 as expected, confirming the Pythagorean identity holds.
  • 2theta = 60.00°, which lies in the first quadrant (both sin and cos positive).

Next stepUse the three cosine forms (cos^2 - sin^2, 2cos^2 - 1, and 1 - 2sin^2) interchangeably depending on which functions are already known in your problem.

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