You should have the basic formula:
The curve has six lobes, so your answer should be greater than 6 times (4 out and 4 in) = 48. And it should be less than 6 times the perimeter of an equilateral triangle with height 4, or 6 times 3 times 8/sqrt(3) = 48sqrt(3).
If you show me your attempt at the problem I can probably help more. Post in this thread and I'll try to answer as soon as possible.