projectile, fired with unknown initial velocity, lands 20 s later on the side of a hill, 3000
m away horizontally and 450 m vertically above its starting point. (a) What is the vertical?
Component of its initial velocity? (b) What is the horizontal component of its initial?
Velocity?
You need to suppress the spurious "?" marks -- confusing and annoying
v sinθ * 20 - 4.9 * 20^2 = 450
v cosθ * 20 = 3000
solve for v and θ, and then you can get the answers to the questions.
Post your work if you get stuck.