解析
|p|=2√3
|q|=√3
|a+b|=√(a+b)²
=√(5p+2q+p-3q)²
=√(6p-q)²
=√(36p²-12pq+q²)
=√(36*8-12*6√2*√2/2+9
=√288-72+9
=√225
=15
已知|向量p|=2根号2,|向量q|=3,且向量p与向量q的夹角为45°,设a=5p+2q,b=p-3q,则|a+b|=?
已知|向量p|=2根号2,|向量q|=3,且向量p与向量q的夹角为45°,设a=5p+2q,b=p-3q,则|a+b|=?
数学人气：787 ℃时间：2020-04-14 15:36:53
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