An architect is planning a new town square the square has sides that are 20 ft long a walkway will also cut diagonally through the square how long will the walkway be

I think u can answer it with a*a+b*b=c*c
this works for right triangles but since a square is 2 right triangles I think it will work
20*20+20*20=c*c
400+400=c*c
800=c*c
c=28.29 ish
the walkway is about 28.29 feet long