$\int{ -\frac{ 1 }{ {t}^{2} } } \mathrm{d} t$
Use the property of integral $\int{ -f\left( x \right) } \mathrm{d} x=-\int{ f\left( x \right) } \mathrm{d} x$$-\int{ \frac{ 1 }{ {t}^{2} } } \mathrm{d} t$
Use $\begin{array} { l }\int{ \frac{ 1 }{ {x}^{n} } } \mathrm{d} x=-\frac{ 1 }{ \left( n-1 \right) \times {x}^{n-1} },& n≠1\end{array}$ to evaluate the integral$-\left( -\frac{ 1 }{ t } \right)$
Substitute back $t=\cos\left({x}\right)$$-\left( -\frac{ 1 }{ \cos\left({x}\right) } \right)$
Simplify the expression$\frac{ 1 }{ \cos\left({x}\right) }$
Add the constant of integration $C \in ℝ$$\begin{array} { l }\frac{ 1 }{ \cos\left({x}\right) }+C,& C \in ℝ\end{array}$