Answer:
a) Â true, B) false, C) true, D) true and E) true
Explanation:
To answer if the statements are correct we must find the initial speeds
  sin 50 = [tex]v_{oy}[/tex] / v
  cos 50 = vₓ / v
   [tex]v_{oy}[/tex] = v sin50
  v₀ₓ = v cos 50
   [tex]v_{oy}[/tex]  = 40 sin 50
  v₀ₓ = 40 cos 50
   [tex]v_{oy}[/tex]  = 30.6 m / s
  v₀ₓ = 25.7 m / s
Let's analyze the questions
A) True. On the x axis there is no acceleration therefore
  v₀ₓ = vₓ,   vₓ = x/t
   x = vₓ t
B) False. Â [tex]v_{oy}[/tex] Â = 40 sin50
        sin50 =  [tex]v_{oy}[/tex]  / 40
C) true. Â vâ‚“ = 40 cos50;
        cos 50 = vₓ / 40
D) true  if the acceleration is in the direction of the velocity
       v = vo + at
E) True  vy = voy - gt
       maximum point vy = 0
        0 = 30.6 - 10 t