argand diagram express z in form a+bi

I used z= r(cos + isin)

which gave me $z= 2(cos(-\pi/3)+ isin(-\pi/3) )$

then simplified to z= 1- sqrt3 i 

but i was wrong and i got told the answer should be 3 - sqrt3i as u add 2 at the end 

can someone explain why please, thanks