Evaluate the following integral using trigonometric substitution.

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{dt}{t^2\sqrt[\phantom{2}]{49-t^2}}$

What substitution will be the most helpful for evaluating this integral?

A$.t=7tan$

B$.t=7sec$

C$.t=7sin$

Rewrite the given integral using this substitution.

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{dt}{t^2\sqrt[\phantom{2}]{49-t^2}}={\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}},d$

$($Type an exact answer.$)$

Evaluate the integral.

${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}\frac{dt}{2\sqrt[\phantom{2}]{sen{x}^2}}=$