The acute angle formula of trigonometric function in junior middle school mathematics formulas of trigonometric functions Daquan
Opposite side/hypotenuse of sinα=∞α
Adjacent edge/hypotenuse of cosα=∞α
Opposite side of tanα = adjacent side of ∠ α/∠α.
Adjacent side of cotα = opposite side of ∠ α/∠α.
Double angle formula
Sin2A=2SinA？ Kosa
cos2a=cosa^2-sina^2= 1-2sina^2=2cosa^2- 1
tan2A=(2tanA)/( 1-tanA^2)
(Note: Sina 2 is the square of Sina 2 (a))
Triple angle formula
sin3α=4sinα？ Sine (π/3+α) Sine (π/3-α)
cos3α=4cosα？ cos(π/3+α)cos(π/3-α)
tan3a=tana？ tan(π/3+a)？ tan(π/3-a)
Derivation of triple angle formula
sin3a
=sin(2a+a)
=sin2acosa+cos2asina
Auxiliary angle formula
Asinα+bcosα = (A2+B2) (1/2) sin (α+t), where
sint=B/(A^2+B^2)^( 1/2)
cost=A/(A^2+B^2)^( 1/2)
tant=B/A
asinα+bcosα=(a^2+b^2)^( 1/2)cos(α-t),tant=a/b
Reduced power formula
sin^2(α)=( 1-cos(2α))/2=versin(2α)/2
cos^2(α)=( 1+cos(2α))/2=covers(2α)/2
tan^2(α)=( 1-cos(2α))/( 1+cos(2α))
Summary of the necessary formulas for the first grade mathematics; The side area of a right prism is s = c * h.
Side area of oblique prism s = c' * h
The side area of a regular pyramid is S= 1/2c*h'
The side area of the prism is s = 1/2(c+c')h'
The lateral area of the frustum of a cone is s =1/2 (c+c') l = pi (r+r) l.
The surface area of the ball S=4pi*r2.
The lateral area of the cylinder is s = c * h = 2pi * h
The lateral area of the cone is s =1/2 * c * l = pi * r * l.
The arc length formula l=a*ra is the radian number r > of the central angle; 0
Sector area formula s= 1/2*l*r
Cone volume formula V= 1/3*S*H
Cone volume formula V= 1/3*pi*r2h
Oblique prism volume V=S'L Note: where s' is the straight cross-sectional area and l is the side length.
Cylinder volume formula V=s*h
Cylinder V=pi*r2h
The common junior high school math formula is 1. There is only one straight line after two o'clock.
2. The line segment between two points is the shortest.
3. The complementary angles of the same angle or equal angle are equal.
4. The complementary angles of the same angle or equal angle are equal.
5. There is one and only one straight line perpendicular to the known straight line.
6. Of all the line segments connecting a point outside the straight line with points on the straight line, the vertical line segment is the shortest.
7. The axiom of parallelism passes through a point outside a straight line, and one and only one straight line is parallel to this straight line.
8. If two straight lines are parallel to the third straight line, the two straight lines are also parallel to each other.
9. The same angle is equal and two straight lines are parallel.
10. The internal dislocation angles are equal and the two straight lines are parallel.
1 1. The inner angles on the same side are complementary and the two straight lines are parallel.
12. Two straight lines are parallel with the same included angle.
13. Two straight lines are parallel and the internal dislocation angles are equal.
14. Two straight lines are parallel and complementary.
15. Theorem The sum of two sides of a triangle is greater than the third side.