Could you guys please help me solve this basic math. PLS OMG ITS DUE :(

The quadratic function h(t) = -16.1t^2 + 150 models a balls height, in feet, over time, in seconds, after its dropped from a 15 story building. from what height in feet was the ball dropped?

Which steps could be part of the process in algebraically solving the system of equations, y+5x=x^2+10 and y=4x-10

Given that sin∅ = 1/4, 0 < ∅ < π/2, what is the exact value of cos∅? a. (√4)/4 b. (√15)/4 c. (4π)/2 d. (4√2)/4