What are the variables in the formula `A=pir^(2)`?

What are the variables in the formula T=2pisqrt((l)/(g)) ?

What are state variables ?

What is state variables ?

The number of variables in the formula T=2pisqrt((l)/(g)) is _____

A spheres has a volume of 36pi . What is the surface area of the sphere? (The surface area of a sphere is given by the formula A=4pir^(2) )