Question

Anita made a wax model of a rolling pin of diameter 6 cm. The rolling pin was shaped like a right circular cylinder with a right circular cone at each end as shown below.

What was the total surface area of the rolling pin? Using complete sentences, describe the steps you used to calculate the surface area.

Answer 1

@satellite73

Answer 2

You find the surface area of the cylinder then the surface area of the 2 cones. Then you subtracted the area of the circle for each SA that you obtained for the cylinder and the 2 cones. Alternatively, you can use the formula pi(d)(h) to find the SA of cylinder that does not include the circles on each end. Same thing with SA of cone, you use formula pi(r)(s) where s is the slanted height, and the formula excludes area of circle.
SA of Cylinder = pi(d)(h) (Excludes the circles)
SA of Cone = pi(r)(s) (Excludes the circle)

So total SA of rolling pin = pi(d)(h) + (pi)(r)(s)
Total SA = pi(6)(9) + pi(3)(4)
Total SA = pi(54) + pi(12)
Total SA = pi(54 + 12)
Total SA = pi(66)
Total SA = 207.24 cm (approximately)

Answer 3

wrong