The motion of a projectile along the horizontal and vertical directions can be analyzed independently by using the equations of motion. Putting ay as minus g and ax as zero for a projectile, the equations simplify.
The initial velocity components obtained by using trigonometric relations further simplify the motion equations.
At the zenith, vy is zero. By substituting vy in the velocity equation for y-direction, time for half-flight is obtained. The zenith height of the projectile can be obtained by substituting the expression for the half-flight time in the displacement equation for y-direction.
The total duration of the flight is twice the time of half-flight. By substituting the total time in the displacement equation in the x-direction, the equation for the maximum range of the projectile is obtained.
The trajectory describes the projectile's path in a 2-dimensional space. Its equation can be obtained by using the position equations.
Rearranging the terms in x-component equation and substituting it in the equation of y-position, we get the final trajectory equation. This equation represents a parabola.