36/sin^2 43°+4+sin^2 133°

[tex]\frac{36}{sin^{2}43 + 4 + sin^{2}133} =  \frac{36}{sin^{2}(30 + 13) + sin^{2}(120 + 13) + 4} =  \frac{36}{\frac{(\sqrt{3}}{2}sin13 + \frac{1}{2}cos13)^2 + (\frac{(\sqrt{3}}{2}cos13 - \frac{1}{2}sin13)^2 + 4} = \frac{36}{sin^{2}13 + cos^{2}13 + 4} =  \frac{36}{5}[/tex]