sin^2α+cos^2α= 1
1+tan^2α=sec^2α
1+cot^2α=csc^2α
Relationship between products:
sinα=tanα×cosα
cosα=cotα×sinα
tanα=sinα×secα
cotα= cosα×csα
secα=tanα×cscα
cscα=secα×cotα
Reciprocal relationship:
tanα cotα= 1
sinα cscα= 1
cosα secα= 1
Relationship between businesses:
sinα/cosα=tanα=secα/cscα
cosα/sinα=cotα=cscα/secα
In the right triangle ABC,
The sine value of angle a is equal to the ratio of the opposite side to the hypotenuse of angle a,
Cosine is equal to the adjacent side of angle a than the hypotenuse.
The tangent is equal to the opposite side of the adjacent side,
[1] trigonometric function identity deformation formula
Trigonometric function of sum and difference of two angles;
cos(α+β)=cosα cosβ-sinα sinβ
cos(α-β)=cosα cosβ+sinα sinβ
sin(α β)=sinα cosβ cosα sinβ
tan(α+β)=(tanα+tanβ)/( 1-tanαtanβ)
tan(α-β)=(tanα-tanβ)/( 1+tanαtanβ)
Trigonometric function of trigonometric sum:
sin(α+β+γ)= sinαcosβcosγ+cosαsinβcosγ+cosαcosβsinγ-sinαsinβsinγ
cos(α+β+γ)= cosαcosβcosγ-cosαsinβsinγ-sinαcosβsinγ-sinαsinαsinβcosγ-sinαsinβcosγ
tan(α+β+γ)=(tanα+tanβ+tanγ-tanαtanβtanγ)/( 1-tanαtanβ-tanβtanγ-tanγtanα)
Auxiliary angle formula:
Asinα+Bcosα=(A? 0? 5+B? 0? 5) (1/2) sin (α+t), where
sint=B/(A? 0? 5+B? 0? 5)^( 1/2)
Cost =A/(A? 0? 5+B? 0? 5)^( 1/2)
tant=B/A
Asinα-Bcosα=(A? 0? 5+B? 0? 5)^( 1/2)cos(α-t),tant=a/b
Double angle formula:
sin(2α)=2sinα cosα=2/(tanα+cotα)
cos(2α)=cos? 0? 5(α)-sin? 0? 5(α)=2cos? 0? 5(α)- 1= 1-2sin? 0? 5(α)
tan(2α)=2tanα/[ 1-tan? 0? 5(α)]
Triple angle formula:
sin(3α)=3sinα-4sin? 0? 6(α)=4sinα sin(60+α)sin(60-α)
cos(3α)=4cos? 0? 6(α)-3 cosα= 4 cosαcos(60+α)cos(60-α)
tan(3α)= tan a tan(π/3+a)tan(π/3-a)
Half-angle formula:
sin(α/2)= √(( 1-cosα)/2)
cos(α/2)= √(( 1+cosα)/2)
tan(α/2)=√(( 1-cosα)/( 1+cosα))= sinα/( 1+cosα)=( 1-cosα)/sinα
Power reduction formula
Sin? 0? 5(α)=( 1-cos(2α))/2 = versin(2α)/2
Because? 0? 5(α)=( 1+cos(2α))/2 = covers(2α)/2
Tan? 0? 5(α)=( 1-cos(2α))/( 1+cos(2α))
General formula:
sinα=2tan(α/2)/[ 1+tan? 0? 5(α/2)]
cosα=[ 1-tan? 0? 5(α/2)]/[ 1+tan? 0? 5(α/2)]
tanα=2tan(α/2)/[ 1-tan? 0? 5(α/2)]
Product sum and difference formula:
sinαcosβ=( 1/2)[sin(α+β)+sin(α-β)]
cosαsinβ=( 1/2)[sin(α+β)-sin(α-β)]
cosαcosβ=( 1/2)[cos(α+β)+cos(α-β)]
sinαsinβ=-( 1/2)[cos(α+β)-cos(α-β)]
Sum-difference product formula:
sinα+sinβ= 2 sin[(α+β)/2]cos[(α-β)/2]
sinα-sinβ= 2cos[(α+β)/2]sin[(α-β)/2]
cosα+cosβ= 2cos[(α+β)/2]cos[(α-β)/2]
cosα-cosβ=-2 sin[(α+β)/2]sin[(α-β)/2]
Derived formula
tanα+cotα=2/sin2α
tanα-cotα=-2cot2α
1+cos2α=2cos? 0? 5α
1-cos2α=2sin? 0? 5α
1+sinα=(sinα/2+cosα/2)? 0? five
* Others:
sinα+sin(α+2π/n)+sin(α+2π* 2/n)+sin(α+2π* 3/n)+……+sin[α+2π*(n- 1)/n]= 0
Cos α+cos (α+2π/n)+cos (α+2π * 2/n)+cos (α+2π * 3/n)+...+cos [α+2π * (n-1)/n] = 0 and
Sin? 0? 5(α)+sin? 0? 5(α-2π/3)+sin? 0? 5(α+2π/3)=3/2
tanAtanBtan(A+B)+tanA+tan B- tan(A+B)= 0
cosx+cos2x+...+cosnx =[sin(n+ 1)x+sinnx-sinx]/2 sinx
Prove:
Left = 2sinx (cosx+cos2x+...+cosnx)/2sinx
= [sin2x-0+sin3x-sinx+sin4x-sin2x+...+sinnx-sin (n-2) x+sin (n+1) x-sin (n-1) x]/2sinx (sum and difference of products)
=[sin(n+ 1)x+sinnx-sinx]/2 sinx = right。
Proof of equality
sinx+sin2x+...+sinnx =-[cos(n+ 1)x+cosnx-cosx- 1]/2 sinx
Prove:
Left =-2sinx [sinx+sin2x+...+sinnx]/(-2sinx)
=[cos2x-cos0+cos3x-cosx+...+cos NX-cos(n-2)x+cos(n+ 1)x-cos(n- 1)x]/(-2 sinx)
=-[cos(n+ 1)x+cosnx-cosx- 1]/2 sinx = right。
Proof of equality
Inductive formula
Formula 1:
Let α be an arbitrary angle, and the values of the same trigonometric function with the same angle of the terminal edge are equal:
sin(2kπ+α)=sinα
cos(2kπ+α)=cosα
tan(2kπ+α)=tanα
cot(2kπ+α)=cotα
Equation 2:
Let α be an arbitrary angle, and the relationship between the trigonometric function value of π+α and the trigonometric function value of α;
Sine (π+α) =-Sine α
cos(π+α)=-cosα
tan(π+α)=tanα
cot(π+α)=cotα
Formula 3:
The relationship between arbitrary angle α and the value of-α trigonometric function;
Sine (-α) =-Sine α
cos(-α)=cosα
tan(-α)=-tanα
Kurt (-α) =-Kurt α
Equation 4:
The relationship between π-α and the trigonometric function value of α can be obtained by Formula 2 and Formula 3:
Sine (π-α) = Sine α
cos(π-α)=-cosα
tan(π-α)=-tanα
cot(π-α)=-coα
Formula 5:
The relationship between 2π-α and the trigonometric function value of α can be obtained by formula 1 and formula 3:
Sine (2π-α)=- Sine α
cos(2π-α)=cosα
tan(2π-α)=-tanα
Kurt (2π-α)=- Kurt α
Equation 6:
The relationship between π/2 α and 3 π/2 α and the trigonometric function value of α;
sin(π/2+α)=cosα
cos(π/2+α)=-sinα
tan(π/2+α)=-cotα
cot(π/2+α)=-tanα
sin(π/2-α)=cosα
cos(π/2-α)=sinα
tan(π/2-α)=cotα
cot(π/2-α)=tanα
sin(3π/2+α)=-cosα
cos(3π/2+α)=sinα
tan(3π/2+α)=-cotα
cot(3π/2+α)=-tanα
sin(3π/2-α)=-cosα
cos(3π/2-α)=-sinα
tan(3π/2-α)=cotα
cot(3π/2-α)=tanα
(higher than k∈Z)
Sine theorem means that in a triangle, the sine of each side is equal to the angle it faces, that is, a/sina = b/sinb = c/sinc = 2r (where r is the radius of the circumscribed circle).
Cosine theorem means that the square of any side in a triangle is equal to the sum of the squares of the other two sides MINUS twice the product of the cosine of the angle between these two sides, that is, A 2 = B 2+C 2-2BC COSA.
The ratio of the opposite side to the hypotenuse of Angle A is called sine of Angle A, and it is recorded as sinA, that is, sinA= the opposite side/hypotenuse of Angle A..
The angle α between the hypotenuse and the adjacent edge.
sin=y/r
Whether y>x or y≤x
No matter how big or small A is, it can be any size.
The maximum value of sine is 1 and the minimum value is-1.
Trigonometric identity
For any non-right triangle, such as triangle ABC, there is always tana+tan b+ tanc = tanatanbanc.
Prove:
It is known that (A+B)=(π-C)
So tan(A+B)=tan(π-C)
Then (tana+tanb)/(1-tanatanb) = (tanπ-tanc)/(1+tanπ tanc)
Surface treatment can be carried out.
tanA+tanB+tanC=tanAtanBtanC
Similarly, we can also prove that when α+β+γ=nπ(n∈Z), there is always tanα+tanβ+tanγ=tanαtanβtanγ.
Vector calculation
Let a=(x, y) and b=(x', y').
1, vector addition
The addition of vectors satisfies parallelogram rule and triangle rule.
AB+BC=AC .
a+b=(x+x ',y+y ').
a+0=0+a=a .
Algorithm of vector addition;
Exchange law: a+b = b+a;
Law of association: (a+b)+c=a+(b+c).
2. Vector subtraction
If a and b are mutually opposite vectors, then the reciprocal of a=-b, b=-a and a+b =0. 0 is 0.
AB-AC=CB。 That is, "* * * the starting point is the same, and the direction is reduced"
A=(x, y) b=(x', y') Then a-b=(x-x', y-y').
4. Multiply the number by the vector
The product of real number λ and vector A is a vector, and λa = ∣ λ ∣∣∣∣∣∣∣∣∣∣∣∣∣.
When λ > 0, λa and A are in the same direction;
When λ < 0, λa and A are in opposite directions;
When λ=0, λa=0, and the direction is arbitrary.
When a=0, there is λa=0 for any real number λ.
Note: By definition, if λa=0, then λ=0 or A = 0.
Real number λ is called the coefficient of vector A, and the geometric meaning of multiplier vector λa is to extend or compress the directed line segment representing vector A. ..
When ∣ λ ∣ > 1, the directed line segment representing vector A extends to ∣λ ∣ times in the original direction (λ > 0) or in the reverse direction (λ < 0);
When ∣ λ ∣ < 1, the directed line segment representing vector A is shortened to ∣ λ ∣ times in the original direction (λ > 0) or in the reverse direction (λ < 0).
The multiplication of numbers and vectors satisfies the following algorithm.
Law of association: (λ a) b = λ (a b) = (a λ b).
The distribution law of vector logarithm (first distribution law): (λ+μ)a=λa+μa 。
The distribution law of number pair vector (second distribution law): λ(a+b)=λa+λb 。
The elimination method of number multiplication vector: ① If the real number λ≠0 and λa=λb, then A = B. ② If a≠0 and λa=μa, then λ = μ.
3. Quantity product of vectors
Definition: the included angle between two nonzero vectors is < a, b > and < a, b > ∈ [0, π].
Definition: the product of two vectors (inner product, dot product) is a quantity, denoted as a B. If A and B are not * * * lines, a b = | a || b | cos < a, b >;; If a, b***, then a b =+-∣ a ∣ ∣ b ∣.
The coordinates of the product of vectors are expressed as: a b = x x'+y y'.
Arithmetic ratio of the product of vectors
A b = b a (exchange rate);
(a+b) c = a c+b c (distribution rate);
Properties of scalar product of vectors
A a = the square of a |.
a⊥b = a b = 0 .
|a b|≤|a| |b| .
The main difference between vector product and real number operation
1, the product of vectors does not satisfy the associative law, that is, (a b) c ≠ a (b c); For example: (a b) 2 ≠ a 2 b 2.
2. The product of vectors does not satisfy the law of elimination, that is, b=c cannot be deduced from A = A = C (A ≠ 0).
3、a | b |≦| a | | b |
4. From |a|=|b|, it is impossible to deduce a=b or a =-b.
Remember that the product of quantities cannot be written as x, otherwise it is wrong. That's the product of difference.