(a) The given information establishes the major and minor axes of the ellipse with its origin at (0,0).
The semi-axes are therefore 50ft and 25ft and the equation in standard form is:
x2/502+y2/252=1, that is: x2/2500+y2/625=1.
(b) and (c) 10ft in from the right vertex is the point (40,0) because the vertex is at (50,0).
Plugging in x=40 into the equation of the ellipse:
1600/2500+y2/625=1,
1600+4y2=2500,
4y2=900, y2=225, y=±15ft, making (40,15) and (40,-15) the endpoints of z. Therefore its length is 30ft.