2) Familiar with various standard curve equations, such as examples, which show that the center of the ball is not at the origin.

3) If there are three unknowns, such as an example, in order to express the spatial position relationship, the term containing one unknown must be zero. Then it is transformed into a plane equation.

4) Simplify and standardize the plane equation and illustrate it with examples.

(x-1) 2+y 2 = 3, which is a cyclic equation.

5) parameterize the plane equation, for example, let (x- 1)=t*cosb, y=t*sinb, and b be the included angle between the vector and the origin. T is the radius of a circle, and it is enough to represent x and y with b and t.

6) Different plane equations have different parameterized standard forms, remember!