[tex] {a}^{2} + {b}^{2} = {c}^{2} \\ ({ \sqrt{47} })^{2} + {b}^{2} = ({10)}^{2} \\ 47 + {b}^{2} = 100 \\ {b}^{2} = 100 - 47 \\ {b}^{2} = 53 \\ b = \sqrt{53} [/tex]
_o_o_
cos k = adjacent / hypotenuse
[tex] \cos(k) = \frac{ \sqrt{53} }{10} [/tex]
I hope I helped you^_^
