Question

The surface area of the rectangular prism below is 286in2. Find the height.

Answer 1

Answer:
`7in`

Explanation:

`Formula: A=2(wl+hl+hw)`

Solve for h;

Let's begin by dividing by 2.

`(A)/(2)=wl+hl+hw`

Subtract wl because it's the only term that doesn't have h.

`(A)/(2)-wl=hl+hw`

Plug your values into the formula.

`(286in^2)/(2)-(5in)(9in) =h(9in)+h(5in)\\143in^2-45in^2=9inh+5inh\\98in^2=14inh`

Divide by 14 to isolate h.

`(98in^2)/(14in)=h`

`7in=h`