Question 940544
To begin with, we can call that triangle {{{scalene}}} ,
meaning that its sides have different lengths.
However, I suspect you are expected to decide if the triangle is a right triangle, an acute triangle, or an obtuse triangle.
  
The largest angle in a triangle is the angle opposite the longest side.
If the angle opposite the side measuring 9 ft were a right angle,
the triangle would be a right triangle;
the longest side (9 ft) would be the hypotenuse,
and the other two sides would be the legs of that right triangle.
 
In a right triangle with legs measuring 3 ft and 8 ft,
the length (in ft) of the hypotenuse is
{{{sqrt(3^2+8^2)=sqrt(9+64)=sqrt(73)}}} .
 
If the length of third side of your triangle were {{{sqrt(73)}}} ft,
the triangle would be a right triangle, but {{{sqrt(73)<>9}}} ,
so the triangle is not a right triangle,
and the angle opposite the 9-ft side is not a right angle.
 
Is it larger than a right angle (an obtuse angle),
or is it smaller than a right angle (an acute angle)
 
{{{9=sqrt(81)>sqrt(73)}}} , so the longest side is longer than {{{sqrt(73)}}} ft.
Since the largest side is longer than needed for a right triangle with legs measuring 3 ft and 8 ft,
the largest angle is larger than a right angle: it is an obtuse angle.
So the triangle is an {{{highlight(obtuse)}}} triangle.