Question

What formulas/equations are used to find the diameter of a circle?

Answer 1

variable "d" usually stands for diameter

If given radius "r"
2*r= d

The circumference of a circle is

`C= 2 \pi r= \pi d`
hence if given circumference

`d= (C)/(\pi)`

The area of a circle is

`A= \pi r^2 = (\pi)/(4) d^2`
hence if given area

`d= \sqrt{(4A)/(\pi)}`