共50条信息
在边长为\(1\)的等边\(\triangle ABC\)中,\(E\)为\(AC\)上一点,且\(\overrightarrow{AC}=4\overrightarrow{AE}\),\(P\)为\(BE\)上一点,且满足\(\overrightarrow{AP}=m\overrightarrow{AB}+n\overrightarrow{AC}(m > 0,n > 0)\),则\(\dfrac{1}{m}+\dfrac{1}{n}\)取最小值时,\(\left| \overrightarrow{AP} \right|=\)__________.
已知\(\Delta ABC\)中的内角为\(A,B,C\),重心为\(G\),若\(2\sin A\overrightarrow{\cdot GA}+\sqrt{3}\sin B\overrightarrow{\cdot GB}+3\sin C\cdot \overrightarrow{GC}=\vec{0}\),则\(\cos B=\)_________.
在\(\triangle ABC\)所在平面内一点\(P\),满足\(\overrightarrow{AP}=\dfrac{2}{5}\overrightarrow{AB}+\dfrac{1}{5}\overrightarrow{AC}\),延长\(BP\)交\(AC\)于点\(D\),若\(\overrightarrow{AD}=\lambda \overrightarrow{AC}\),则\(\lambda =\)_______.
如图,在\(\Delta ABC\)中,\(\overrightarrow{CD}=2\overrightarrow{DB}.\)若\(\overrightarrow{AD}=x\overrightarrow{AC}+y\overrightarrow{BC}(x,y\in R)\),则\(x-3y\)的值为________.
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