Question: I need your help again

Hello!

1)Dr:=[[1,5],[2,6],[3,4],[4,5],[5,7],[6,8],[7,4],[8,6],[9,5],[10,7]]:

2)Y:=proc(i) Dr[i,2] end;ty:=proc(i) Dr[i,1] end;

3)P[X](omega)=(1/2)*{(Sum(Y(j)*cos(omega*(ty(j)-1/(2*omega*tan((Sum(sin(2*omega*ty(j)),j=1..N[0]))/(Sum(cos(2*omega*ty(j)),j=1..N[0]))))))^2,j=1..N[0]))/(Sum(cos(omega*(ty(j)-1/(2*omega*tan((Sum(sin(2*omega*ty(j)),j = 1..N[0]))/(Sum(cos(2*omega*ty(j)),j=1..N[0]))))))^2,j= 1..N[0]))+(Sum(Y(j)*sin(omega*(ty(j)-1/(2*omega*tan((Sum(sin(2*omega*ty(j)),j=1..N[0]))/(Sum(cos(2*omega*ty(j)),j=1..N[0]))))))^2,j=1..N[0]))/(Sum(sin(omega*(ty(j)-1/(2*omega*tan((Sum(sin(2*omega*ty(j)),j=1..N[0]))/(Sum(cos(2*omega*ty(j)),j =1 .. N[0]))))))^2,j=1..N[0]))};

1) and 2) are known, I want to count 3, but I can not.

Thanks...