Double angle formula calculator

The double angle identity calculator finds the value of a double angle for any trigonometric function if the value of an angel is provided. This calculator can compute values of:

• Sin2x
• Cos2x
• Tan2x

What is a double angle?

Double angle, as the words imply, means to increase the size of the angle to twice its size. It simply means two times of a trigonometric angle i.e 2x in terms of x. 

Double angle identities are used to simplify trigonometric calculations. 

Double angle formula

The main formulas used to find a double angle are:

• Sin2x = 2 (sinx).(cosx)
• Cos2x= 2.cos²x -1
• tan2x = (2.tanx)/(1 - tan²x) 

You can also calculate half angle of trigonometric identities by using our half angle identity calculator.

How to find a double angle?

You can learn to find the double angle through an example.

Example

What is the double angle for sin 40°?

Solution

Step 1: Write the formula of sin2x.

Sin2x = 2 (sinx).(cosx)

Step 2: Put the value of the angle into the formula.

Sin2x = 2 (sin 40).(cos 40)

= 2 (0.642)(0.766)

= 0.9836