What is the kinetic energy of an ideal projectile of mass 19.4 kg at the apex (highest point) of its trajectory, if it was launched with an initial speed of 29.2 m/s and at an initial angle of 46.9° with respect to the horizontal?

Question

I know kinetic energy equals half of mass times velocity squared but the launching at a certain angle is throwing me off here

Answer 1

Vo = 29.2m/s @ 46.9o
Xo = 29.2*Cos46.9 = 20.0 m/s.
Yo = 29.2*sin46.9 = 21.32 m/s.

V = Xo + Yi = 20 + 0i = 20 m/s @ h max.

KE = 0.5m*V^2 = 0.5*19.4*20^2 = 3880 J.