The integrals below involve `cot ax`.
1) `int cot ax dx = 1/a ln sin ax`
2) `int cot^2 ax dx = -(cot ax)/a-x`
3) `int cot^3 ax dx = -(cot^2 ax)/(2a)-1/a ln sin ax`
4) `int cot^n ax*csc^2 ax dx = -(cot^(n+1)ax)/((n+1)a)`
5) `int (csc^2ax)/(cotax) dx = -1/aln cot ax`
6) `int 1/(cot ax) dx = -1/a ln cos ax`
7) `int x*cotax dx = 1/a^2{ax-(ax)^3/9-(ax)^5/225-...-(2^(2n)B_n(ax)^(2n+1))/((2n+1)!)-...}`
8) `int (cot ax)/x dx = -1/(ax)-(ax)/3-(ax)^3/135-...-(2^(2n)B_n(ax)^(2n-1))/((2n-1)(2n)!)-...`
9) `int x*cot^2 ax dx = -(x cot ax)/a+1/a^2 ln sin ax-x^2/2`
10) `int 1/(p+q cot ax) dx = (px)/(p^2+q^2)-q/(a(p^2+q^2))ln(p sin ax+q cos ax)`
11) `int cot^n ax dx = -(cot^(n-1) ax)/((n-1)a)-int cot^(n-2) ax dx`