共50条信息
\(\Delta {A} {B} {C}\)的内角\({A} \),\({B} \),\({C}\)所对的边分别为\(a\),\(b\),\(c\).向量\(\vec{m}=\left( a,\sqrt{3}b \right)\)与\(\vec{n}=\left( \cos {A} ,\sin {B} \right)\)平行.
\((1)\)求\({A} \);
\((2)\)若\(a=\sqrt{7}\),\(b=2\)求\(\Delta {A} {B} {C}\)的面积.
已知向量\(a\)\(=(1,2)\),\(b\)\(=(-3,2)\),当\(k\)为何值时,
\((1)ka\)\(+\)\(b\)与\(a\)\(-3\)\(b\)垂直?
\((2)ka\)\(+\)\(b\)与\(a\)\(-3\)\(b\)平行?平行时它们是同向还是反向?
进入组卷