Pre Calc Homework, any help is appreciated!

Question

A hangar is formed of a half cylinder with a rectangular base and two open, semicircular ends. The curved roof costs $7 per ft2 to build. Find an expression that represents the cost per volume of the hangar (dollars/ft3) to build the curved roof. Your cost should be a function of the radius r of the semicircular end. 

 

I'm not even sure what formulas to use 

Answer 1

I'm pretty sure we are going to have to use the formula for the surface area of a cylinder which would be

 

S = 2PI R ( H + R )

 

But since we have semi circles we are going to use PIR^2 + PITH

 

V = 7 × ( PIR^2 + PIRH)

 

that ought to be your expression I assume hope I helped and the answer to your problem on zombies was 3417 as you had mentioned.