.8087
  PAGE 60,132
  .MODEL SMALL
  .STACK 32
  .DATA
  ORG 00H
  R DD 91.67
  ORG 10H
  AREA DD ?
  .CODE
  START PROC FAR
  MOV AX,@DATA
  MOV DS,AX
  CALL CIRC_AREA
  MOV AH,4CH
  INT 21H
  START ENDP
  CIRC_AREA PROC NEAR
  FINIT 
  FLD R 
  FMUL ST(0),ST(0) 
  FLDPI 
  FMUL ST(0),ST(1) 
  FSTP AREA 
  RET
  CIRC_AREA ENDP
  END START