What is tan2α equal to?

Double angle formula: tan2a = 2tana/[ 1-(tana) 2].

Double angle formula is a set of formulas commonly used in mathematical trigonometric functions. The trigonometric function value of double angle 2α is expressed by some transformation relations of trigonometric function value of angle α. The angle doubling formula includes sine angle doubling formula, cosine angle doubling formula and tangent angle doubling formula. It can be used to simplify the calculation formula and reduce the number of trigonometric functions in calculation, and it is also widely used in engineering.

Formulas of trigonometric functions is a function formula of transcendental function in elementary function in mathematics. Their essence is the mapping between the set of arbitrary angles and a set of ratio variables, and the usual trigonometric functions are defined in the plane rectangular coordinate system.

Formula 1: Let α be an arbitrary angle, and the values of the same trigonometric function with the same terminal edge angle are equal:

sin( 2kπ +α)=sinα(k∈Z).

cos(2kπ+α)=cosα(k∈Z).

tan(2kπ+α)=tanα(k∈Z).

cot(2kπ+α)=cotα(k∈Z).

Tips for memory: Even and odd are unchanged, and the sign looks at the quadrant, that is, if the shape is (2k+1) 90 α, the function name becomes a remainder function, sine becomes cosine, cosine becomes sine, tangent becomes cotangent, and cotangent becomes tangent. If the shape is 2k×90 α, the function name remains unchanged.

Formula (sine and cosine angle sum difference formula):

The symbols of shell family are the same, but the symbols of shell family are different.

1) Sine sum and difference have the same sign, but cosine sum and difference have different signs.

2) The sine sum difference formula is always the product of sine and cosine; Cosine sum and difference formula is always cos times cos and sin times sin.