Answer:
Part 1) 
Part 2) The surface area is
or 
Part 3)
or 
Step-by-step explanation:
Part 1) How much material does he need to cover the one rectangular side of the tent with the rip?
we know that
The area of a rectangle is equal to

we have


substitute the values
Part 2) If David’s dad wanted to re-cover the whole tent including the bottom, how much material would he need?
we know that
The surface area of a triangular prism (the tent) is equal to

where
B is the area of the triangular face
P is the perimeter of the triangular face
L is the length of the triangular prism
<em>Find the area of the triangular face B</em>
<u><em>Note </em></u><em>The height of the triangle cannot be equal to 6 ft. The height of a right triangle cannot be equal to the hypotenuse. The height must be calculated by applying Pythagoras theorem</em>
we have

Find the height applying the Pythagoras Theorem
substitute the values



substitute
<em>Fin the perimeter of the triangular base P</em>

<em>Find the surface area SA</em>

-----> exact value
or
-----> approximate value
Part 3) What is the volume of the tent?
we know that
The volume of the tent is equal to

where
B is the area of the triangular face
L is the length of the tent
we have

substitute

-----> exact value
or
-----> approximate value