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# Double Angle Sine/Cosine Calculator Online

sin(2θ):

cos(2θ):

The Double Angle Sine/Cosine Calculator helps you find the sine and cosine values for double angles efficiently. By using this calculator, you can quickly determine the values of sine and cosine for an angle that is twice the given angle. This tool is particularly useful in trigonometry, physics, and engineering, where precise angle calculations are essential.

### Formulas of Double Angle Sine/Cosine Calculator

#### Double Angle Formula for Sine

The double angle formula for sine is:

sin(2θ) = 2 * sin(θ) * cos(θ)

This formula allows you to calculate the sine of twice an angle if you know the sine and cosine of the original angle.

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#### Double Angle Formula for Cosine

The double angle formulas for cosine can be written in three equivalent forms:

cos(2θ) = cos²(θ) – sin²(θ)

Alternatively, using the Pythagorean identity, this formula can also be expressed as:

cos(2θ) = 2 * cos²(θ) – 1

or

cos(2θ) = 1 – 2 * sin²(θ)

These formulas enable you to compute the cosine of double an angle based on the sine and cosine of the original angle.

### Pre-calculated Values Table

Below is a table with commonly used double angle values for sine and cosine:

This table provides quick reference values, saving you time from manual calculations.

### Example of Double Angle Sine/Cosine Calculator

Let’s consider an example to demonstrate how to use the Double Angle Sine/Cosine Calculator.

Suppose you want to find the sine and cosine of 2θ when θ is 45 degrees.

1. Calculate sin(θ) and cos(θ) for θ = 45 degrees:
• sin(45) = 0.707
• cos(45) = 0.707
2. Use the double angle formulas:
• sin(2 * 45) = 2 * sin(45) * cos(45)
• sin(90) = 2 * 0.707 * 0.707 ≈ 1
• cos(2 * 45) = cos²(45) – sin²(45)
• cos(90) = 0.707² – 0.707² = 0

Therefore, sin(90) = 1 and cos(90) = 0.

### Most Common FAQs

How accurate is the Double Angle Sine/Cosine Calculator?

The calculator provides highly accurate results based on the input values. It uses precise mathematical formulas to ensure reliability for academic and professional purposes.

Can I use the Double Angle Sine/Cosine Calculator for negative angles?

Yes, the calculator works for both positive and negative angles. The double angle formulas apply universally, ensuring correct results for any given angle.