Answer the following for a primitive cubic unit cell. Answers should be numerical, set r = 8.0

Question

-edge in terms of r, the lattice pt radius:___
-face diagonal in terms of r, the lattice pt radius:___
-body diagonal in terms of r, the lattice pt radius:___

Answer the following for a face centered unit cell.Answers should be numerical, set r = 6.0.
-edge in terms of r, the lattice pt radius:___
-face diagonal in terms of r, the lattice pt radius:___
-body diagonal in terms of r, the lattice pt radius

Please help.I will truely appreciate it..

Answer 1

Do you mean by help that you want us to work the problems for you. Tell us what you don't understand and perhaps we can get you started. You might also explain what pt stands for.

Answer 2

I know that the edge for the first one is 2r so in terms of r the lattice point (pt) would = 16.
To find the face diagonal using the Pythagorean theorem it would be (2r)^2+(2r)^2= (face diagonal)^2.. But every time I would plug it in, its incorrect.
And for the body diagonal, I'm lost...

Answer 3

For r=6.0
6(2)= 12
12(squ root 2) = 16.97056
12(squ root 3) = 20.7846

And for r=8.0, do the same steps.
Hope that helps!

Answer 4

the 3rd part its
sqrt(a^2+b^2+c^2)