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Auxiliary angle formula
Auxiliary angle formula is an advanced formula of trigonometric function, and the algebraic expression used is asinx+bcosx=√(a? +b? )sin(x+φ)[a & gt; 0,φ=arctan(b/a)∈(-π/2,π/2)]

The main function of this formula is to turn the sum of multiple trigonometric functions into one function, thus solving the maximum problem. Auxiliary angle formula is widely used in mathematics. The main function of this formula is to turn the sum of multiple trigonometric functions into one function, thus solving the maximum problem.

Many people often forget whether the arc tangent is b/a or a/b when using the auxiliary angle formula, which leads to mistakes in doing problems. In fact, there is a very convenient memory skill, that is, whether sine or cosine is used to represent asinx+bcosx, the position of denominator is always used to represent the coefficient of function name. If asinx+bcosx is expressed by sine, then the arc tangent is b/a (that is, the coefficient a of sine is in the denominator). If expressed in cosine, the arctangent becomes a/b (the coefficient b of cosine is in the denominator).

Common formulas of trigonometric functions.

1, sum and difference product formula

The sum-difference product formula is one of trigonometric functions, which represents the relationship between two trigonometric functions. By adding or subtracting the values of two trigonometric functions, we can get their sum-difference products. This formula can help people understand and master the properties and relationships of trigonometric functions.

2. Half-angle formula

Half-angle formula is one of trigonometric functions, which is used to calculate sine, cosine and tangent of half-angle. According to the half-angle formula, knowing the angle of the angle and the three vertices of the triangle, we can calculate the rest of the chords, cosines and tangents. Half-angle formula plays a very important role in trigonometric function, which helps us to master the basic concepts and operations of trigonometric function.

Refer to the above content: Baidu Encyclopedia-Auxiliary Angle Formula