[tex]\displaystyle\\\frac{\sin(4\!\propto)}{\sin^2(2\!\propto)}=\frac{2\sin(2\!\propto)\cos(2\!\propto)}{\sin(2\!\propto)\sin(2\!\propto)}=\frac{2\cos(2\!\propto)}{\sin(2\!\propto)}=\boxed{\bf2\text{\bf ctg}(2\!\propto)}[/tex]
