Pythagorean theorem: the distance relationship between two points on three straight lines, that is, a2+b2=c2.
2. Cosine theorem: two right triangles formed by two intersecting straight lines, c2=a2+b2+abXcosC.
3. Sine theorem: two right triangles formed by two intersecting straight lines, sina/a = sinb/b = sinc/c.
4. trapezoidal formula: the sum of areas, that is, (a+b)h/2.
5. Formula of circular area: r2.
6. Triangle area formula: S = 1/2 xbxsinc.
7. Parabolic area formula: S= 1/3XaXh2.
8. Secant rule:1/y =1/a+1/b.
9. Pythagorean deformation theorem: ac=a2+b2-2abcosC.
10, cotangent theorem: tana/a = tanb/b = tanc/c.
1 1, Helen's formula: triangle inner angle A+B+C = 180, a2=b2+c2-2bccosA.
12, congruence triangle theorem: triangle inner angle a/a = b/b = c/c.
The importance of mathematics:
1. Mathematics is not only an important science, but also a basic science, with the characteristics of surpassing specific scientific and universal application.
Mathematics is very useful to our daily life.
3. Learning mathematics is conducive to better cultivating the ability to think and solve problems.