Question

A pendant is formed using a cylinder and cone. Once assembled, as shown below, the pendant is painted. How many square millimeters are covered with paint? Express the answer in terms of π.

Answer 1

Answer:

Step-by-step explanation:

336pi

Answer 2

Surface area of cylinder is given by area of circle + area of the rectangle that curved around the cylinder

Area of the base of the cylinder = $\pi r^{2} = 8^{2} \pi =64 \pi$
Area of the cylinder 'wall' = width × length = $12$×$2r \pi$=$12$×$16 \pi$=$192 \pi$

Note that the wall of the cylinder is in the shape of a rectangle. The width of the rectangle is the height of the cylinder. The length of the rectangle is the circumference of the circle base.

Surface area of cone is given by $\pirl$ where $l$ is the slanted height of the cone

SA of cone = $\pi (8)(10)=80 \pi$

Hence total painted surface area is $80 \pi +192 \pi +64 \pi =336 \pi$