So let's start off by drawing the FCC structure. And we know that an eighth of an atom goes in each corner. And an atom goes on the faces. Now I'm going to shade in the slices to show you that it's just a portion of the atom that's in this of CC structure. So the planar packing factor for the 1, 1, 0 plane. Let's write the formula. So the number, so it's area of atoms on the plane all over the area of the plane. The 1, 1, 0 plane goes right across the diagonal. I'll draw it out bigger over here. So it's like a rectangle. And I'll draw the reduced sphere model, which means that I'm not drawing so that the atoms touch, but they are there. And so in this plane, only a portion of these, the ones that I'm coloring in, are actually counted as part of the planar packing factor. So only these atoms. And we also know that at the bottom it's 1, 2, 3, 4, R. But at the side, it's just A. So let's find the number of atoms on this plane. We have 1, 2, 3, 4, it's 4 times a quarter plus 1, 2 times a half. This gives us 2 atoms. Perfect. Now we want to find out the area of the plane. The area of the plane is A times 4R. It is a rectangle, after all. And A for an FCC is 2 root 2R. So 2 root 2R times 4R. So that's a 2. So you have 8 root 2R for your area. Now let's continue with our first equation. Area of the atoms on the plane. So we have 2 atoms times the area of 1 atom is a circle, pi or squared. And the area of our plane is 8 root 2, that is an R squared, R squared. And so if I were to continue that down here, we will get the planar packing factor of the 1, 1, 0 plane is. So let's calculate that pi all over 4 root 2.