can someone help me with this step by step?

2. For 27.5MeV alphas on 208Pb a) what impact parameter corresponds with scatter to 60 degrees? b) what is the distance of closest approach? c) Experimentally, this is when we find the alpha and Pb start to fuse. From the distance of closest approach, and assuming everything spherical, extract R0 from the R=R0A1/3 equation. (This is not the same as, but not too far from, what we find using electron scattering. It's a bit different from the class example since we're not shooting the alpha straight in, so SHOW WORK.)