A projectile is launched from the ground at t=0 with an initial launch speed of v0 m/s at and angle of degree above the horizontal. at t = 3 sec, the project its reaches its highest point. At t = 4 sec, the projectile lands on the top edge of edge of a cliff (marked with a). The distance among the point of launch and the base of the cliff is 60 m.
What is the speed of the projectile at the top of its trajectory?