The sum of triangles is 180.

Big side to big corner, small side to small corner.

The triangle area formula s= 1/2 base * height.

Pythagorean Theorem of Right Triangle A 2+B 2 = C 2

Y = ax 2+bx+c unary quadratic equation function

Vieta theorem x1+x2 =-b/a.

x 1*x2=c/a

Trigonometric function value sin 30= 1/2 sin45= root number 2/2 sin60= root number 3/2 sin 90= 1.

Polynomial simplification, factorization, a 2-b 2 = (a+b) (a-b)

a^2+b^2+2ab=(a+b)^2

The diagonal of the parallelogram is bisected, and the three sides of the triangle are equal, with an included angle of 60.

Tangent formula of triangle, chord center distance formula of circle, area formula of circle.

Congruence, similar triangles's judgment formula, corresponding edge proportion formula, etc.

Formula of equal ratio theorem, formula of combined ratio theorem,