# Double angle formula calculator

To find the value of sin2x, cos2x, or tan2x, put the angle in the 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