Given that,
Angle θ=450
Velocity u=20√2m/s
We know that,
The time of flight
t=2usinθgcosθ
t=2×20√210×1
t=5.7s
Now, the horizontal range is
R=u2sinθgcosθ
R=20√2×20√210
R=80m
Hence, this is the required solution