Question

Jack knows the surface area of a cylinder and its radius. He wants to find the cylinder's height. He needs to rewrite the formula A=2πr (r+h) to find the cylinder's height (h) in terms of the cylinder’s surface area (A) and its radius (r). Which is the correct formula?

a. h= r+ A/2πr
b. h= A/2πr
c. h= A/2πr-r^2
d. h= A/2πr-r

Answer 1

A=2πr (r+h)
We divide both sides of equation by "2πr"
A/(2πr)=2πr (r+h) / (2πr)
A/(2πr)=r+h

r+h=A/(2πr)
We have to subtrac "r" both sides of the equation:
r+h-r=A/(2πr)-r
h=A/(2πr) - r

Answer: d.h=A/2πr-r

Answer 2

The answer is the option D

`h=(A)/(2\pi r) -r`

Explanation:

we know that

The formula to calculate the surface area of a cylinder is equal to

`A=2\pi r(r+h)`

where

A is the surface area of the cylinder

r is the radius of the cylinder

h is the height of the cylinder

Isolate the variable h

Divide by
`2\pi r` both sides

`A/(2\pi r)=(r+h)`

Subtract
`r` both sides

`h=(A)/(2\pi r) -r`