Answer
$\frac{\sqrt {13}}{7}$
Work Step by Step
$sin^{2}t$ + $cos^{2}t$ = 1
sin t = $\frac{6}{7}$
$(\frac{6}{7})^{2}$ + $cos^{2}t$ = 1
$\frac{36}{49}$ + $cos^{2}t$ = 1
$cos^{2}t$ = 1 -$\frac{36}{49}$
$cos^{2}t$ = $\frac{13}{49}$
cos t = $\sqrt \frac{13}{49}$ = $\frac{\sqrt {13}}{7}$
