Root formula: x
=-b radical b? -4ac/2a
General form: ax? +bx+c
Parabola: y=a(x-h)? +k
Intersection point: d < r
Tangency: d=r
Separation: d > r
Vertex: (-b/2a, 4ac-b? /4a)
Second: products
X 1X2=-b/a
and
X 1+X2c/a
Sum of polygon interior angles: (n-2)* 180