The velocity must be broken down into x (horizontal) and y (vertical) components. We can use the y component to find how high the object gets. To find vertical velocity, vy, use vy=vosinθ.
vy=(75ms)sin45o=53ms
Next we find how long it takes to reach the top of its trajectory using vf=vo+at.
0ms=53ms+(−10ms2)t
t = 5.3s
Finally, find how high the object goes with d=vot+12at2.
