Question

the horizontal range of a projectile is 4a. It passes a tower that height a/2 when the horizontal range was a. What is the projectile velocity and projectile angle.

Answer 1

"Range" is how far the projectile travels when it hits the ground

The horizontal range cannot be both 4a and a. Do you mean the height was a/2 when it had travelled a distance a?

Answer 2

Yes