Now I can actually edit my answer directly: I'm fairly sure I've got this wrong, and my mind has gone blank for how to do it, if someone could delete this that would be great and I'll think about it and see if I can figure it out!
Answer:

Explanation:
As we know that the formula of range is given as

now we know that
maximum value of the range of the projectile is given as

now we need to find such angles for which the range is half the maximum value
so we will have




No, speed is not a vector. it is scalar.
because it doesn't need direction but need magnitude.
Answer:
you can build a mote around your castle and put crocodiles in it.
Explanation:
they will have to go in the water to get to your castle and will get eaten.