Needing some help outlining the steps of the two questions here

Question

1. The surface area of a cylinder is 170π cmsquared.

Calculate the height of the cylinder.

 

2. A cylinder has a surface area of 400π cmsquared, a height of x and a diameter of 2x. 

Calculate x.

 

Thanks

Answer 1

For a cylinder: 

 S.A. = 2πr²+2πrh     in this formula,  r is the radius and h is the height.

 S.A. = (area of circles) + (area of tube part)

 

To solve question 1, you actually need to know what the radius is. Otherwise you have one equation with two unknowns.

 

The setup for question 2 is the same formula, except you'd plug in x for the height instead of h. Since the diameter is twice the radius, r is also equal to x. Just apply the formula above. You can cancel π out and things simplify to 400 = 4x². 

 

Hope this helps. If you need more help, let me know. 

Answer 2

1. Cannot be determined without additional information

2. 400π = πx² + 2πx²