Answer :
[tex]\dfrac{\tan t}{\cos t}\\\\\\=\dfrac{\tan t \cdot \cos t}{\cos t \cdot \cos t}\\\\\\=\dfrac{\sin t}{\cos^2 t}\\\\\\=\dfrac{\sin t}{1 - \sin^2 t}\\[/tex]
[tex]\dfrac{\tan t}{\cos t}\\\\\\=\dfrac{\tan t \cdot \cos t}{\cos t \cdot \cos t}\\\\\\=\dfrac{\sin t}{\cos^2 t}\\\\\\=\dfrac{\sin t}{1 - \sin^2 t}\\[/tex]