Question

已知向量a与b夹角为60°,向量a的模=2,向量b的模=1,求向量a+b的模,向量a-b的模.

要有过程哦！

Answer 1

解
/a/=2
/b/=1
a*b=/a//b/cos60=1
/a+b/
=√(a+b)²
=√(a²+b²+2ab
=√4+1+2=√9
=3
/a-b/=√(a-b)²
=√(a²+b²-2ab
=√4+1-2
=√3