A rocket is launched at an angle of 42◦ above the horizontal with an initial speed of 76 m/s. It moves for 9 s along its initial line of motion with an acceleration of 29 m/s^2. At this time

its engines fail and the rocket proceeds to move as a projectile.
The acceleration of gravity is 9.8 m/s^2.

a.) Find the maximum altitude reached by the rocket.
b.) What is its total time of flight?
c.) What is its horizontal range?

I know how to find these with constant acceleration (I think) but with the increasing acceleration I'm not sure.

Answers are:

a.) 3837.91 m
b.) 59.9965 s
c.) 14152.7 m

Need to know how to solve, thank you.