Answer:
The dart won't hit within 1.00 cm of the bullseye
Step-by-step explanation:
First, we need to calculate the time that the dart takes to hit the dartboard. This can be calculated using the distance of 5.7 m and the horizontal speed of 21.3 m/s, so

Then, with this time we can calculate the change in height of the dart, using the following equation

Where vo is the initial vertical velocity, so vo = 0 m/s, g is the gravity, so g = 9.8 m/s², and t is 0.268 s.
So, replacing the values, we get:

Since Δy is greater than 1 cm, the dart will not hit within 1.00 cm of the bullseye. So, to adjust the shot, you should release the dart from 35.09 cm above.