Current location - Training Enrollment Network - Mathematics courses - What is the mathematical formula of the first volume of the seventh grade?
What is the mathematical formula of the first volume of the seventh grade?
Mathematical formulas that must be memorized in the first volume of the seventh grade;

I. formulas of trigonometric functions

1, sum of two angles formula

sin(A+B)= Sina cosb+cosAsinBsin(A-B)= Sina cosb-sinBcosA

cos(A+B)= cosa cosb-Sina sinb cos(A-B)= cosa cosb+Sina sinb

tan(A+B)=(tanA+tanB)/( 1-tanA tanB)tan(A-B)=(tanA-tanB)/( 1+tanA tanB)

2. Double angle formula

tan2A = 2 tana/( 1-tan2A)ctg2A =(ctg2A- 1)/2c TGA

cos2a = cos2a-sin2a = 2 cos2a- 1 = 1-2 sin2a

Second, the area formula:

Side area of right-angle prism 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.

Third, the commonly used formula of factorization.

1, square difference formula: a? -B? =(a+b)(a-b)

2. Complete square formula: a? +2ab+b? =(a+b)?

3. Cubes and formulas: A? +b? =(a+b)(a? -ab+b? )

4. Cubic difference formula: a? -B? =(a-b)(a? +ab+b? )

5. Complete cubes and formulas: a? +3a? b+3ab? +b? =(a+b)?

6. Complete cubic difference formula: a? -3a? b+3ab? -B? =(a-b)?

7. Three complete square formulas: A? +b? +c? +2ab+2bc+2ac=(a+b+c)?

8. Three cubes and formulas: A? +b? +c? -3abc=(a+b+c)(a? +b? +c? -ab-bc-ac)

Four, the area formula of common graphics

Area of rectangle = length× width S=ab

Area of a square = side length × side length S=a?

Area of triangle = base × height ÷2S=ah÷2

Area of parallelogram = base × height S=ah

Trapezoidal area = (upper bottom+lower bottom) × height ÷2S=(a+b)h÷2.

Area of circle = π× radius× radius

Five, perimeter formula

Circle: C=πd=2πr (d is diameter, r is radius, π).

The circumference of a triangle is C = a+b+c(abc is three sides of a triangle).

Quadrilateral: C=a+b+c+d(abcd is the side length of quadrilateral)

Rectangle: C=2(a+b) (a is long and b is wide)

Square: C=4a(a is the side length of the square)

Polygon: C= sum of all sides.

Sector circumference: C = 2R+nπR÷ 180? (n= central angle) = 2R+kR (k= radian)