
theorem Th10:
  for n, i being Nat holds [** cos((2*PI*i)/n), sin((2*
  PI*i)/n)**] = [** cos((2*PI*(i mod n))/n), sin((2*PI*(i mod n))/n) **]
proof
  let n, i be Nat;
  [** cos((2*PI*i)/n), sin((2*PI*i)/n)**] = [** cos((2*PI*(i mod n))/n),
  sin((2*PI*i)/n)**] by Th9
    .= [** cos((2*PI*(i mod n))/n), sin((2*PI*(i mod n))/n) **] by Th9;
  hence thesis;
end;
