向量|a|=3^(1/2),|b|=2^(1/2),ab=-3^(1/2),|axb|的值为
问题描述：
向量|a|=3^(1/2),|b|=2^(1/2),ab=-3^(1/2),|axb|的值为
答
夹角的余弦值为-3^(1/2)/[3^(1/2)*2^(1/2)] = -1/2^(1/2)
所以其正弦值为{1-[-1/2^(1/2)]^2} ^(1/2) = 1/2^(1/2)
所以|axb| = 3^(1/2) * 2^(1/2) *1/2^(1/2) = 3^(1/2)