Three large water pipes run through the building. Enigeneers plan to enclose these water pipes within a ceramic-coated triangular casing to prevent radiation. Each of the water pipes has an outside diameter of 60 cm. If the cross section of the casing is an equilateral triangle, what is the smallest length possible?

*I got this problem to do with a group but i have no idea how to do it. smart math people please help. its due 1st perioid!