Prove: \[\left( \mathbf{1}\text{ }+\text{ }\mathbf{ta}{{\mathbf{n}}^{\mathbf{2}}}~\mathbf{A} \right)\text{ }\mathbf{cot}\text{ }\mathbf{A}/\text{ }\mathbf{cose}{{\mathbf{c}}^{\mathbf{2}~}}\mathbf{A}\text{ }=\text{ }\mathbf{tan}\text{ }\mathbf{A}\] contexto.140 3 years ago