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Mathematical formula in the second volume of the eighth grade
What are the mathematical formulas in the second volume of the eighth grade? Next, I will bring you the mathematical formula in the second volume of Grade 8 for your reference.

Mathematical formula in the second volume of the eighth grade:

Multiplication and factorization A2-B2 = (a+b) (a-b) A3+B3 = (a+b) (A2-AB+B2) A3-B3 = (A-B (A2+AB+B2))

Trigonometric inequality |a+b|? |a|+|b| |a-b|? |a|+|b| |a|? B<=>- b? Answer? b |a-b|? |a|-|b| -|a|? Answer? |a|

Solution of quadratic equation in one variable-B+? (b2-4ac)/2a -b-? (b2-4ac)/2a

The relationship between root and coefficient x1+x2 =-b/ax1* x2 = c/a.

Note: Vieta theorem discriminant b2-4ac=0 Note: The equation has two equal real roots B2-4ac >;; 0

Note: This equation has two unequal real roots B2-4ac.

Note: The equation has no real root, but has a plurality of yokes.

The formula of the sum of two angles of trigonometric function

sin(A+B)=sinAcosB+cosAsinB

sin(A-B)=sinAcosB-sinBcosA

cos(A+B)=cosAcosB-sinAsinB

cos(A-B)=cosAcosB+sinAsinB

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

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

Sine theorem a/sinA=b/sinB=c/sinC=2R.

Note: where r represents the radius of the circumscribed circle of the triangle.

Cosine theorem b2=a2+c2-2accosB

Note: Angle B is the standard equation (x-a)2+(y-b)2=r2 containing a circle between side A and side C..

Note: (a, b) is the general formula x2+y2+Dx+Ey+F=0.

Note: D2+E2-4f > 0 parabola standard equation y2 = 2pxy2 =-2pxy2 = 2pxy2 =-2pxy

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 * r.

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*r a is the radian number r > of the central angle; 0

Sector formula s= 1/2*l*r

Cone volume formula V= 1/3*S*H

Cone volume formula

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