Asolid piece of wood shaped as a cylinder with an 8-centimeter diameter is cut as shown.

what is the surface area of the figure? express the answer in terms of π.

96 + 64π cm2
96 + 80π cm2
96 + 112π cm2
96 + 128π cm2

The surface area of the figure is 96 + 64π ⇒ 1st answer

Step-by-step explanation:

* Lats revise how to find the surface area of the cylinder

- The surface area = lateral area + 2 × area of one base

- The lateral area = perimeter of the base × its height

* Lets solve the problem

- The figure is have cylinder

- Its diameter = 8 cm

∴ Its radius = 8 ÷ 2 = 4 cm

- Its height = 12 cm

∵ The perimeter of the semi-circle = πr

∴ The perimeter of the base = 4π cm

∵ The area of semi-circle = 1/2 πr²

∴ The area of the base = 1/2 × π × 4² = 8π cm²

* Now lets find the surface area of the half-cylinder

- SA = lateral area + 2 × area of one base + the rectangular face

∵ LA = perimeter of base × its height

∴ LA = 4π × 12 = 48π cm²

∵ The dimensions of the rectangular face are the diameter and the

   height of the cylinder

∴ The area of the rectangular face = 8 × 12 = 96 cm²

∵ The area of the two bases = 2 × 8π = 16π cm²

∴ SA = 48π + 16π + 96 = 64π + 96 cm²

* The surface area of the figure is 96 + 64π

u rich

step-by-step explanation: