||'''Book'''|| Linear Algebra ||
 ||'''Author'''|| Gilbert Strang ||
 ||'''Edition'''||  ||

/* code_begins */

{{{
a=vector([2,-2,1])
b=vector([1,2,2])
arccos ((a.dot_product(b))/norm(a)*norm(b))
}}}

/* code_ends */

 * '''Solution by''': 
   * <manisha>, <student>, <SNIST>
   * <deepthi>, <student>, <SNIST>