在\({\triangle }ABC\)中,\(BC{=}7{,}AC{=}6{,}\cos C{=}\dfrac{2\sqrt{6}}{7}{.}\)若动点\(P\)满足\(\overrightarrow{{AP}}{=}(1{-}\lambda)\overrightarrow{{AB}}{+}\dfrac{2\lambda}{3}\overrightarrow{{AC}}{,}(\lambda{∈}R)\),则点\(P\)的轨迹与直线\({BC}{,}{AC}\)所围成的封闭区域的面积为\(({ })\)