`D = 12/(1 + tan^2 73^o) - 4tan75^o . cot105^o + 12sin^2 . 107^o - 2 tan40^o . cos60^o . tan50^o`

`\begin{array}{l}D = 12{\cos ^2}{73^ \circ } + 12{\sin ^2}\left( {{{180}^ \circ } - {{73}^ \circ }} \right) - 4\tan {75^ \circ }.\cot \left( {{{180}^ \circ } - {{75}^ \circ }} \right) - 2\tan {40^ \circ }.\tan \left( {{{90}^ \circ } - {{40}^ \circ }} \right)\cos {60^ \circ }\\D = 12{\cos ^2}{73^ \circ } + 12{\sin ^2}{73^ \circ } - 4\tan {75^ \circ }\left( { - \cot {{75}^ \circ }} \right) - 2\tan {40^ \circ }.\cot {40^ \circ }.\frac{1}{2}\\D = 12 + 4 - 1 = 15\end{array}`