What are the formulas for a triangle and what is the formula for a triangle?

Trigonometric formulas have the following that must be known:

sin²x +cos²x = 1

Symbolic transformations: sin(-x)=-sinx cos(-x)=cosx tan(-x) and cot(-x) I don't need to talk about it.

As for sin(x+(n 2)) and the like, it is still "odd and even, and the symbol looks at the quadrant".

Additive: sin(x+y)=sinxcosy+sinycosx cos(x+y)=cosxcosy-sinxsiny

Take y=x : sin2x=2sinxcosx cos2x=cos x-sin x=(1-sin x)-sin x=1-2sin x=2cos x-1

Take y=-z: sin(x-z)=sinxcosz-sinzcosx cos(x-z)=cosxcosz+sinxsinz

Sum difference product: sinx+siny ; Let (x+y) 2 =m (x-y) 2=n then m+n=x,m-n=y

sinx+siny=sin(m+n)+sin(m-n)=2sinmcosn=2sin[(x+y)/2]cos[(x-y)/2]

sinx-siny=2sin[(x-y)/2 ]cos[(x+y)/2]

Sum difference: sinxcosy = [sin(x+y)+sin(x-y)] 2

sinxsiny=[cos(x-y)-cos(x+y)]/2

cosxcosy=[cos(x+y)+cos(x-y) ]/2

tanx: ⑧tanx=sinx/cosx=sin²x/(cosxsinx)=2sin²x/2cosxsinx=(1-cos2x)/sin2x

2sinxcosx /2cos²x=sin2x/(1+cos2x)

That's all, and there are things like sin3x and universal formulas that you can know but don't need to master.

The sum of the three angles is 180 degrees.

If there is more of it, if I say the formula of the triangle, I may not report it to play next month.

The formula for a triangle is:1. The area is high at the bottom 2.

2. S=AH2 (S area, A bottom, H height).

3. The height of the triangle is 2 bottoms (S area, A bottom, Laxiao H height).

4. The bottom area of the triangle is 2 high (S area, A bottom, H high).

5. Number of triangles.

nth n(n+1) 2=(n +n) 2. The nth number of squares is n.

Nature of the Triangle:1. The sum of the internal angles of the triangle is equal to 180° (the sum of the internal angles and theorem) on the plane.

2. The outer corner of the triangle on the plane.

The sum is equal to 360° (the sum of the outer angles and theorem).

3. On the plane, the outer angles of the triangle are equal to the sum of the two inner angles that are not adjacent to it.

4. At least two of the three inner angles of a triangle are acute.

5. At least one angle in the triangle is greater than or equal to 60 degrees, and at least one angle is less than or equal to 60 degrees.

6. The sum of the seepage on any two sides of the triangle is greater than the third side, and the difference between any two sides is less than the third side.

7. In a right triangle.

, if an angle is equal to 30 degrees, then the right-angled edge opposite by the 30-degree angle is an hypotenuse.

of half. 8. The sum of the squares of the two right-angled sides of a right-angled triangle is equal to the square of the hypotenuse (Pythagorean theorem.

9. The middle line of the hypotenuse of a right triangle is equal to half of the hypotenuse.

10. The three angular bisectors of a triangle.

At one point, the straight line where the three high lines are located intersects at one point, and the three middle lines meet at one point.