The formula of double angle is: double cosine is equal to the square of minus cosine, double sine is equal to double sine multiplied by cosine, and double tangent is equal to the square of minus tangent.

Double angle formula is one of the important formulas in mathematics, which is used to calculate the trigonometric function value corresponding to double angle. Mastering the double-angle formula can help us simplify the calculation and understand the problem, thus improving the ability of mathematical application.

Double angle formula of 1. cosine

The angle-doubling formula of cosine means that twice the cosine is equal to the square of one minus cosine. The specific expression is cos(2θ)= 1-2sin? θ. This formula can be derived from the definition of trigonometric function and the properties of cosine function. In practical application, the angle-doubling formula can help us to calculate cosine values at different angles, thus solving various problems such as trajectory and angle measurement of objects in engineering.

2. Sine polygonal formula

The angle-doubling formula of sine means that twice sine equals twice sine times cosine. The specific expression is sin(2θ)=2sinθcosθ. This formula can also be derived from the definition of trigonometric function and the properties of sine function. In practical application, the angle-doubling formula can help us to calculate sine values from different angles, such as vibration and wave problems in mechanics, electromagnetism and other fields.

3. Tangent polygon formula

The multiple angle formula of tangent means that twice the tangent is equal to the square of one MINUS the tangent. The specific expression is tan(2θ)=( 1-tan? θ)/( 1+tan？ θ)。 This formula can also be derived from the definition of trigonometric function and the properties of tangent function. In practical application, the double angle formula can help us to calculate the tangent value at different angles, such as mechanical problems and mechanical problems in physics, engineering and other fields.

4. Application example

Double-angle formula is widely used in mathematics and practical application. For example, in geometry, we often need to calculate the trigonometric function value corresponding to twice the angle. At this time, the double angle formula can help us simplify the calculation process. In addition, in physics, engineering and other fields, the double angle formula is also widely used to solve various complex problems, such as mechanical problems, wave problems, vibration problems and so on.