if z1=-1 and z2=i then find (1)arg z1.z2(2)arg (z2/z1)

here x and y are smaller and greater than 0 respectivelyso,arg z1=pie* and z2=pie*/2(1) arg z1.z2=arg z1 +arg z2= pie*+ pie*/2= 3pie*/2(2)arg (z2 / z1)=argz2-argz1=pie*/2-pie*=(-pie*/2)