Answer:
The answer is "1160 ft".
Explanation:
Using the Pythagoras theorem:
[tex]\to a= 280 \times 3= 840\\\\\to b= 400 \times 2= 800\\\\[/tex]
[tex]\bold{\to y^2= a^2+b^2}\\\\[/tex]
[tex]=840^2 +800^2\\\\= 705600+640000\\\\=1345600\\\\=1160 \ ft\\[/tex]
[tex]\to y=1160 \ ft[/tex]