test the convergence or divergence for sum of (cosnpie)/n^(3/4)

my work:

(cosnpie)/n^(3/4) is similar to pie/(n^3/4)

lim as n goes to infinity is (cosnpie)/n^(3/4)times(n^3/4)/pie equals infinity

so the series diverges by limit comparison test

is this right?