Question 53903
I am not sure how you're supposed to be solving this.  There are several ways to do it.
Slope corresponds with the tangent of an angle, but we don't have to use that definition unless you're required to right now.
It is also {{{m=rise/run}}}
The run is 5 mi.
We don't know the rise, let rise=y
Slope = .25
Your equation is:
{{{.25=y/(5 mi)}}}
{{{.25(5 mi)=(5mi)y/(5mi)}}}
{{{1.25mi=cross(5mi)*y/cross(5mi)}}}
y=1.25 mi
The plane's highth at this time is 1.25 mi at after it has flown a horizontal distance of 5 mi.
Happy Calculating!!!!