Draw "right triangle" and label the ground as (x) and label the height as (y). Since you only have x & y, you must use tangent to get the answer.
To revisit trig functions, tangent is y/x.
To set it up, you will have tan 22 = y / 7850. This will become as y = 7850 tan 22
7850 * tan 22 = 7850 * 0.4040262258351568 = 3171.6058728 feet ---> 3171.6 or 3172 ft
To Check it:
3172 / 7850 = tan θ
take inverse tangent:
tan-1(3172 / 7850) = tan-1(tan θ) tan-1(0.404076433121) = θ
θ = 22.0024793968681 = 22 degrees
It works out.
I hope you understood. Good luck to you.