Question

Three vectors which are coplanar with respect to a certain rectangular co-ordinate system are given by a = 4 hati - hatj, b = - 3hati + 2hatj and c =- 3hatj Find (a) a+b+c (b) a+b+-c (c ) Find the angle between a+b+c and a+b-c

Answer 1

Answer:

a)hati-2hatj b)hati+4hatj c)139.39 degree

Explanation:

a)a+b+c=(4-3)hati+(-1+-3+2)hatj=hati-2hatj

b)a+b-c=(4-3hati+(-1+2+3)hatj=hati+4hatj

c)cos theta=m*n/|m||n|=(1*1)+(-2*4)/|sqrt(17)||sqrt(5)|. to find theta=cos inverse of that value=139.39 degree