consider the gravity constant **g = - 9.81**

*Initial conditions (t = 0 s) *

lets find the initial speed components vx and vy

i) Speed and Angle @ t=4s

the x component doesn't change

the y component changes because of gravity

Speed is a vector, not a scalar.

You probably want the norm...

Now finding the angle is easy.:

θ = -23.2º means 23.2º

*below* horizontal

ii) Finding the maximum height

we need to find the time corresponding to that moment -

since:

and

plug this value in the y(t) equation and find the max height.

And that's it!