a 120° sector is cut out of a circular piece of tin with radius 6 in. and bent to form the lateral surface area of a cone. What is the volume of the cone?

I assume that the radius of 6 inches becomes the slant height but what am I supposed to do to find everything else needed to find the volume? What does the 120 degrees cut out have to do with it? Please explain this for me, the test is tomorrow and my brother the tutor isn't home tonight

Thanks!