Answer
$ a=6.71;A=73.4^{\circ}; B=16.6^{\circ}$
Work Step by Step
The trigonometric ratios are as follows: $\sin \theta= \dfrac{opposite}{hypotenuse}$ ; $\cos \theta= \dfrac{Adjacent}{hypotenuse}$ and $\tan \theta= \dfrac{Opposite}{Adjacent}$
$\cos A=\dfrac{2}{7} \implies A=73.4^{\circ}$
So, $ B=90^{\circ}- 73.4^{\circ}=16.6^{\circ}$
and $ a= c\sin A=7 \sin 73.4^{\circ}=6.71$
Thus, $ a=6.71;A=73.4^{\circ}; B=16.6^{\circ}$
