Online calculator for circle segment arc length, chord length and area 
Give Inputs in Yellow colour cell    
S.No Description Values UOM
1 Dia of the Circle   mtr
2 Perpendicular  length from circle chord to circle edge  mtr
Result 
1 Total Area of the Circle m2
2 Angle of the segment Deg.
3 Chord length of the circle segment mtr
4 Arc  Length of the circle segment    mtr
5 Area of the segment  m2
6 Circle area except segment   m2