The textbooks say that the maximum range for projectile motion (with no air resistance) is 45 degrees. How do you get this? Here we go.

But the effect of gravity should look the same. Now, if we put this vertical acceleration together with the fixed horizontal velocity, we get something special, called projectile motion.

Projectile motion problems can easily become algebra problems that focus on identifying the right number in a diagram and substituting it into the correct equation.