In the middle of a statics problem full of unknowns, and am trying to simplify a sum of moments down to the point where I have: a= everthing else (a as a function of several other terms). Keep getting close, but then always have an extra variable or two that won't go anywhere. Here's the equation (the k is just noting a unit vector, so ignore): http://www.ihostphotos.com/show.php?id=192455 The first thing I did was multiply through by a factor of sqrt(a^2 + 4r^2) to get rid of that factor in two of the denominators and the sqrt sign on the other, but then it just started getting REALLY messy. Can anyone figure out what this equation (in the pic) should be, as "a=...." only?? The other variables in that are: P, L, r, and Nb.