Motion in a Plane: Projectile Hits Ground 7.5s Later

[Lydia22]

Homework Statement

A projectile is fired with an initial speed of 30m/s at an angle of 60° above the horizontal.The object hits the ground 7.5s later.
a)How much higher or lower is the launch point relative to the point where the projectile hits the ground?

Homework Equations

The Attempt at a Solution

a)u(y)=30sin60,u(x)=30cos60
v=u+at
=30sin60-9.8*7.5
=47.52 downwards
tanθ=V(y)/V(x)
=(-47.53/30cos60)
=72.48° below the x-axis
therefore,the launch point is 72.48°-60°=12.45° above relative to the point where the projectile hits the ground.

 

[azizlwl]

The vertical displacement, y, is the point where the projectile hits the ground.

 

[Lydia22]

Isn't the vertical displacement zero?