What are the formulas for geometry circle?

5 pi r3 trust me its right even my teacher said so if your teacher teaches it differently he/she is wrong, my teacher proved it to me

Formula of a circle in cartesean plane:(x-k)2+ (y-h)2 = r2

pi. r2 = area 2pi. r=circumference of circle.

Okay, if you're talking about area then you need to find that. You do this by Aria equals pi times the radius squared. You can split a circle up so many times that if you put them beside each other...

to get the circumference: you take the diameter and times it by pi (3.14)to get the area: take the radius (diameter divided by 2) and square it. for example, the diameter is 6. then the radius is 3....