Question

已知向量a,b满足向量a的模=1,向量b的模等于2,向量a与b的夹角为60度,则（向量a-b）的模

Answer 1

|a-b|^2=a^2+b^2-2a*b=a^2+b^2-2|a||b|cos60
=1+2^2-2*1*2*0.5
=3
|a-b|=根号3