Hi大家好我是赤蛇，这期介绍一下dse数学中equation of circles的知识点。这期不出完，如果点赞多的话会出下一期。

Forms

Standard Form (Center-radius Form)

圆心：C(h, k)

半径：r

Standard Form: (x-h)2+(y-k)2=r2.

General Form

圆心：(h, k)=(-D/2, -E/2)

半径：r=√[(D/2)2+(E/2)2-F]=√(h2+k2-F)

x2+y2+Dx+Ey+F=0

Different Types of Circles

Consider the radius of a circle C: x2+y2+Dx+Ey+F=0

Real Circle

(D/2)2+(E/2)2-F>0, r>0

Point Circle

(D/2)2+(E/2)2-F=0, r=0

Imaginary Circle

(D/2)2+(E/2)2-F<0, r<0