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#eb1d361e-791f-489c-a71a-b128c39adf07简单解答题空间向量求角与距离立体几何

19. 已知空间三点A(1A(-11-12)2)B(0B(0,1,0)0)C(2C(-2,3,1)1),设a=BA\overrightarrow{a}=\overrightarrow{BA}b=BC\overrightarrow{b}=\overrightarrow{BC}c=AC\overrightarrow{c}=\overrightarrow{AC}
(1)判断ΔABC\Delta ABC的形状;
(2)若(2a+kb)//c({-2\overrightarrow{a}+k\overrightarrow{b}})//\overrightarrow{c},求kk的值.