## 14.
Geometric characteristics of
flat figures

The function /
Geometry / main menu of
the program includes the following options:

/ Surface area A /

/ center of gravity
<xs, ys> /

/ static moment S /

/ moment of inertia J /

/ central moments of inertia and strength indices Jx, Jy, Wx, Wy
/

/ closed area test

Any enclosed area is calculated. Specifying boundaries of enclosed
area is identical to specifying an hatching area.

After finding a closed area, it is filled with current color
(temporarily, until any key is pressed) in order to verify the
correctness of the given area boundaries.

The calculated value (or values) are displayed in the top info
line. After pressing any key, the drawing is redrawn (the area filled
is removed) and the calculated values are saved in the notepad (for
later use if necessary).

All value are expressed in current units, taking into account the
scale of the current drawing.

The surface area is expressed in current drawing measure units to
the power of 2.

The coordinates of the center of gravity are expressed in the
local system of the drawing.

Static moments are expressed in current drawing measure units to
the power of 3.

Moments of inertia are expressed in current drawing measure units
to the power of 4.

The central moments of inertia (Jx, Jy) are determined with
respect to the axes parallel to the X and Y axes, passing through the
area's center of gravity. At the same time, the strength indices (Wx,
Wy) in relation to both central axes expressed in drawing units to
the power of 3 are calculated.

All values are determined by numerically integrating the closed
area.