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Key formula of junior one mathematics
If you want to learn mathematics well, it is very important to master mathematical formulas and keep them in mind. The following summarizes the key formulas of junior one mathematics, hoping to help everyone.

Geometry 1, square:

Perimeter = side length ×4 C=4a

Area = side length × side length S=a×a

2. Cube:

Surface area = side length × side length× ×6 S Table =a×a×6

Volume = side length × side length × side length v = a× a× a.

3. Rectangular:

Circumference = (length+width) ×2 C=2(a+b)

Area = length × width S=ab

4. Cuboid:

Surface area (length× width+length× height+width× height )× 2s = 2 (AB+AH+BH)

Volume = length× width× height V=abh

Multiplication and factorization (a+b)(a-b)=a? -B?

(A and B)? =a? 2ab+b?

(a+b)(a? -ab+b? )=a? +b?

(a-b)(a? +ab+b? )=a? -B?

Answer? +b? =(a+b)? -2ab

(a-b)? =(a+b)? -4ab

Power operation 1. Multiplication of the same base power: a m ×a n =a (m+n).

2. power (a m) n = a (mn), product (ab) n = a nb n

3. Division of the same base power: a m÷÷an n = a (m-n).

4. Zero index: a 0 = 1.

Acute angle formula of formulas of trigonometric functions trigonometric function

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))

When the linear function is proportional, the quotient of x and y is certain. In the inverse proportional function, the product of x and y is definite. In y=kx+b(k, b is constant, k≠0), when x increases by m times, the function value y increases by m times; On the contrary, when x is reduced by m times, the function value y is reduced by m times.

1. Find the k value of the function image: (y 1-y2)/(x 1-x2).

2. Find the midpoint of the line segment parallel to the X axis: |x 1-x2|/2.

3. Find the midpoint of the line segment parallel to the Y axis: |y 1-y2|/2.

4. Find the length of any line segment: √ (x 1-x2) 2+(y 1-y2) 2 (note: the sum of squares of (x1-x2) and (y1-y2) under the root sign).