7.
对于非零向量\( \overset{⇀}{a} \)、\( \overset{⇀}{b} \),给出以下结论:
\(①\)若\( \overset{⇀}{a} /\!/ \overset{⇀}{b} \),则\( \overset{⇀}{a} \)在\( \overset{⇀}{b} \)方向上的投影为\(| \overset{⇀}{a} |\);\(②\)若\( \overset{⇀}{a} ⊥ \overset{⇀}{b} \),则\( \overset{⇀}{a} ⋅ \overset{⇀}{b} =( \overset{⇀}{a} ⋅ \overset{⇀}{b} )^{2}\);
\(③\)若\( \overset{⇀}{a} ⋅ \overset{⇀}{c} = \overset{⇀}{b} ⋅ \overset{⇀}{c} \),则\( \overset{⇀}{a} = \overset{⇀}{b} \); \(④\)若\(| \overset{⇀}{a} |=| \overset{⇀}{b} |\),且\( \overset{⇀}{a} \),\( \overset{⇀}{b} \)同向,则\( \overset{⇀}{a} > \overset{⇀}{b} \).
其中所有正确结论有: ;