PLANE

AREA CALCULATOR in centimeters, I don't know if it makes a difference

PYTHAGOREAN: The Square of the Hypotenuese is equal to the square of the other two sides or a^{2}+b^{2}=c^{2}

CHORD/CIRCUMFERENCE CALC by Jeff LeMieux (this guy is *good*!).

AREA OF REGULAR N-SIDED POLYGON