I'm guessing its maths cause g=10. Ah actually it doesn't really matter cause you get the same formula anyway
at 1 sec, the height of the projectile without gravity is
, which you can get by integrating with g=0. WITH gravity, the height at 1 sec is
which you get by integrating with g=10. Subtract the height with gravity at 1 sec from the height without gravity at 1 sec and the usinθ's cancel out nicely, leaving 5m.
Similarly at 2 seconds, you would do the same, giving the height without gravity at 2 as
, and with gravity gives
. subtracting these cancels the sines out nicely giving 20m.
Do the same for 3 sec and you should get 45m
If this is physics, the formula is just s=ut+1/2 at^2, and everything works out the same