Junior high school mathematics must recite the equation 1. The lateral area of the frustum: S = 1/2(c+c')l = pi(R+R)l, and the surface area of the ball: S = 4pi * R2；;
2. cylindrical lateral area: S=c*h=2pi*h, conical lateral area: s =1/2 * c * l = pi * r * l;
3. Arc length formula: l=a*r, where a is the radian number of the central angle r > 0, and the sector area formula: s =1/2 * l * r;
4. Cone volume formula: V= 1/3*S*H, cone volume formula: v =1/3 * pi * R2h;
5. Volume of oblique prism: V=S'L, note: where s 'is the area of straight section and l is the length of side;
6. Cylinder volume formula: V=s*h, cylinder: v = pi * R2h.
7. Sine theorem: a/sinA=b/sinB=c/sinC=2R, note: where r represents the radius of the circumscribed circle of a triangle;
8. Cosine theorem: b2=a2+c2-2accosB. Note: Angle B is the included angle between side A and side C;
9. The standard equation of a circle: (x-a)2+(y-b)2=r2. Note: (a, b) is the central coordinate;
10. General equation of circle: x2+y2+Dx+Ey+F=0, note: d2+e2-4f > 0;
1 1. Parabolic standard equation: y2=2px, y2=-2px, x2=2py, x2 =-2py;
12. lateral area of straight prism: S=c*h, lateral area of oblique prism: s = c' * h;
13. lateral area of regular pyramid: S = 1/2c * h', lateral area of regular prism: S = 1/2(c+c')h'.
Formulas of trigonometric functions (1) two-angle sum 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
The formula skillfully remembers the knowledge points of junior high school mathematics 1, and the addition of rational numbers: the addition of the same number is one-sided; Different symbols add "big" and subtract "small". The sign is equal to the big and the absolute value is equal. Zero is just right.
2. Merge similar items: Merge similar items, and the rules should not be forgotten, just seek the sum of coefficients, and the letters and indexes remain unchanged.
3. Square difference formula: There are two square difference formulas. Remember that the symbols are opposite, multiply the beginning and end by the end, and don't confuse it with the complete formula.
4. Complete square formula: there are three complete squares, the first and last symbols are fellow villagers, the first square and the last square, and the first and second squares are placed in the middle; The first and last brackets are square, and the symbol of the last item follows the center.
5. Conditions of the simplest radical: the simplest radical has three conditions, the denominator is not included in the symbol, the power exponent (root exponent) should be coprime, and the power exponent is less than the root exponent.