A solid cylinder cut into two equal parts and placed side by side. If the diameter of the cylinder is 7cm and the height is 8cm, find the total surface area of the two parts. (Answer given in the book is 365cm square)

Question

anonymous · Answer

do you know how to find surface area of the full cylinder

anonymous · Answer

$$full _{SA}+rectangles_{SA}=2 \pi r^2+2\pi rh=2\pi \frac{7}{2}(\frac{7}{2}+8)+2(7)(8)$$

anonymous · Answer

I know the formula is 2pi r(r+h)

anonymous · Answer

yes so how much you get when you put radius r=7/2  and h=8

anonymous · Answer

Sorry I duno how you get this figure from the formula u stated 
2pirsquare + 2pirh = 2pi7/2(7/2+8) + 2(7)(8)
but what i get is 2pi7/2square + 2pi7/2(8) = 253

Can you explain this please? Thanks so much for your time

anonymous · Answer

on the answer you gt you are supposed to add 2(7)(8)

anonymous · Answer

253+112=365

anonymous · Answer

oops ok i understand already thanks! ^^