Calculation of the area of common forms of dirt-guard systems

The outer part of a revolving door

A rectangle

a side length (mm)
b side length (mm)
R radius length (mm)
h chord length (mm)

Result

The area of the outer part of a revolving
door:

A trapeze

a side length (mm)
b side length (mm)
h height (mm)

Result for the trapeze

The area of the outer part of a revolving
door:

The inner part of a revolving door

r radius length (mm)
R radius length (mm)

Result

The area of the inner part of a revolving
door: