use of pi in plane and solid geometry?

Answer 1

Examples of pi in plane geometry:

The circumference of a circle is π times its diameter:

C = πd

The area of a circle is π times the square of its radius:

A = πr²

Examples in solid geometry:

The volume of a cylinder is π times the square of the radius times the height:

Vcyl = πr²h

The volume of a sphere is 4/3 time π times the cube of the radius:

Vsph = 4/3πr³