pi = 3.141592
      GOTO 40
     
10    CLS
      s = 0
      a = pi / 2.5
     
20    s = s + 1: IF s > 99 THEN GOTO 40
      fa = TAN(a) - a - b
      IF ABS(fa) = ABS(bfa) THEN GOTO 30
      bfa = fa
      dfa = (1 / COS(a) ^ 2 - 1)
      a = a - fa / dfa
      PRINT "Num:"; s, "f:"; fa; "    ", "Angle:"; a * 180 / pi
      GOTO 20

30    PRINT
      PRINT "Num:"; s, "Angle:"; a * 180 / pi

40    PRINT
      INPUT "INV Value: "; b
      GOTO 10