Double Angle Identities Calculator

Find the value of double angles through this double angle identity calculator. Simply enter the value of angle, select unit, and trigonometric function. In the end, click “calculate”

Double Angle Trig Identity

Double Angle Formula Calculator 

Double angle identities solver (Calculator) uses trig identity formula to solve the expression of trigonometric functions of angles equal to 2θ in terms of θ.

What is a double angle?

As the name suggests, the double angle is two times an angle i.e 2θ. These angles are represented by 

  • Sin2x
  • Cos2x
  • Tan2x

These identities are used in the solution process of complex trigonometry.

Double angle formula:

Trigonometry formulas are used to find double angles. Most common ones are

  • Sin2y = 2 (siny).(cosy)
  • Cos2y= cos2(y) - sin2(y) 
  • Tan2y = (2.tany)/(1 - tan2y)

Some of these formulas can be rearranged to derive more formulas.

How to find a double angel? 


Find the double angle. The value of the angle is cos 30°.


Step 1: Write the formula of cos2y.

Cos2y= cos2(y) - sin2(y) 

Step 2: Put the value of the angle in the above formula.

Cos2y= cos2(30) - sin2(30) 

Cos2y= (√3/2)(√3/2) - (½)(½)

Cos2y= ½ or 0.5