Vertical Motion Homework Problem

[rg3po]

Homework Statement

A rock is thrown vertically upward from the edge of a cliff. The rock reaches a maximum height of 18.6 m above the top of the cliff before falling to the base of the cliff, landing 6.60 s after it was thrown. How high is the cliff? Assume gravity= 9.8m/s²

Homework Equations

Vy_f=Vy_o + at
Y=Y_o + 1/2(Vy_o+Vy_f)t
Y=Y_o + Vy_ot + 1/2at²
Vy_f²=Vy_o²+ 2a(y-y_o)

The Attempt at a Solution

I don't know where to start. I must figure out initial speed and the difference between the cliff and the max height. Is the initial position 0 at the height of the cliff or at the max height? Do I care that when the ball reaches the max height the speed is 0?EDIT:Figured it out, I had the dumb for few minutes

 

[azizlwl]

Solve it graphically, velocity vs. time.