How far from the starting point do the pieces fall on ground?

Question

An object is thrown with speed 20 m/Sunder the angle pi/3 rad with the horizontal direction. In the highest point, the object is divided into two pieces with same weights. One of them, after the division has the speed 0. 
How far from the starting point do the pieces fall on ground?

The piece that has the speed 0:
x1=v0^2sin2a/2g=17.32 m
x2=v0^2sin2a/g=34.64 m
The answer in the book is 10, 20 meters.

Comments

This is not graduate-level, voting to close.