10.
在平面直角坐标系中,\(O\)为坐标原点,\(A\)、\(B\)、\(C\)三点满足\( \overset{→}{OC}= \dfrac{1}{3} \overset{→}{OA}+ \dfrac{2}{3} \overset{→}{OB} \).
\((1)\)求证:\(A\)、\(B\)、\(C\)三点共线;
\((2)\)已知\(A(1, \)
\(\cos x\)\()\)、\(B(2 \)
\(\cos \)\({\,\!}^{2} \dfrac{x}{2} \),
\(\cos x\)\()\),
\(x\)\(∈[0, \dfrac{x}{2} ]\),若
\(f\)\(( \)
\(x\)\()= \overset{→}{OA} ⋅ \overset{→}{OC} -(2\)
\(m\)\(+ \dfrac{2}{3} )| \overset{→}{AB} |\)的最小值为\(-1\),求实数
\(m\)值\(.\)
\((3)\)若点\(A(2,0)\),在
\(y\)轴正半轴上是否存在点\(B\)满足\({ \overset{→}{OC}}^{2} = \overset{→}{AC} ⋅ \overset{→}{CB} \),若存在求出点\(B\);若不存在,请说明理由.