k = tanα=(y2-y 1)/(x2-x 1)
2. The distance formula of a straight line,
Let P(x0, y0) and the linear equation is: Ax+By+C=0.
Then the distance from p to the straight line is: d=|Ax0+By0+C|/√(A? +B？ )
3. Vieta theorem
If y=ax? +bx+c=0 (a≠0) has real roots, so the relationship between these two roots is
X 1+X2 =-B after one minute, and X 1 X2 = C after one minute.
4. Necessary and sufficient conditions
(1) Sufficient condition: If p→q, then p is a sufficient condition of q. 。
(2) Necessary condition: If q→p, then P is the necessary condition of Q. 。
(3) Necessary and sufficient conditions: If p→q and q→p, then P is a necessary and sufficient condition of Q. 。
Note: If A is a sufficient condition for B, then B is a necessary condition for A; or vice versa, Dallas to the auditorium
5. Trigonometric function
The formula of (1) sum of two angles
sin(A+B) = sinAcosB+cosAsinB
sin(A-B) = sinAcosB-cosAsinB
cos(A+B) = cosAcosB-sinAsinB
cos(A-B) = cosAcosB+sinAsinB
(2) Double angle formula
Sin2A=2SinA？ Kosa
Cos2A = Cos2A-Sin2A = 2 Cos2A- 1 = 1-2 Sin2A
(3) Triple angle formula
sin3A = 3sinA-4(sinA)3
cos3A = 4(cosA)3-3cosA
tan3a = tana？ Tan (+a)? sepia
(4) Sum and difference of products
sinasinb = - [cos(a+b)-cos(a-b)]
cosacosb = [cos(a+b)+cos(a-b)]
sinacosb = [sin(a+b)+sin(a-b)]
cosasinb = [sin(a+b)-sin(a-b)]
(5) Inductive formula
Sin(-a)=- Sina
cos(-a) = cosa
sin( -a) = cosa
Cos( -a) = Sina
sin( +a) = cosa
Cos(+a)=- Sina
sin(π-a) = sina
cos(π-a) = -cosa
sin(π+a) = -sina
cos(π+a) = -cosa
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 the trigonometric function values of 2π-α and α can be obtained by Formula-and Formula 3:
Sine (2π-α)=- Sine α
cos(2π-α)= cosα
tan(2π-α)= -tanα
Kurt (2π-α)=- Kurt α