The diameter of acilindrical unshapen pencil 8mm and its length 17.5 cm find the surface area?

3 answers

as with all cylinders of radius r and height (or length) h,
a = 2πr^2 + 2πrh = 2πr(r+h)
your radius is 4mm and length is 175mm, so plug and chug.
I will assume you meant:
a cylindrical unsharpened pencil ????

In that case, surface area is
2πr^2 + 2πrh
= 2π(4^2) + 2π(4)(175) mm^2
= 128π + 1400π mm^2
= 1528π mm^2 or 15.28π cm^2 -----> since 1 cm^2 = 100 mm^2
l want question