Respuesta :
Ellis will need 259.05 unit paint to paint all surfaces of 11 fenceposts.
What is the surface area of a cylinder ?
If, Radius of the cylinder be r and height of the cylinder be h,
Then, Surface area (A) = [tex]2\pi rh+2\pi r^{2}[/tex] sq. unit
How to find the amount of paint needed for Ellis ?
Ellis is painting wooden fenceposts which are of cylindrical shape.
The height of a fencepost (h) = 7 feet
The diameter of a fencepost = 1 foot
So, The radius of a fencepost (r) = [tex]\frac{1}{2}[/tex] foot
Given, the value of [tex]\pi[/tex] is 3.14
∴ Surface area of a fencepost (A) = [tex]2\pi rh+2\pi r^{2}[/tex]
= (2×3.14×[tex]\frac{1}{2}[/tex]×7)+(2×3.14×[tex](\frac{1}{2} )^{2}[/tex]) sq. feet
= (21.98+1.57) sq. feet
= 23.55 sq. feet
For 1 fencepost, Paint needed = 23.55 unit
For 11 fenceposts, Paint needed = 23.55×11 unit
= 259.05 unit
Hence, 259.05 unit paint needed for 11 fenceposts.
Learn more about surface area here :
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Answer:
259.05 ft²
Step-by-step explanation:
Each fence post can be modeled as a cylinder.
Surface area of a cylinder
[tex]\sf SA=2 \pi r^2+2 \pi rh[/tex]
where:
- r = radius
- h = height
Given:
- diameter = 1 ft ⇒ r = 0.5 ft
- h = 7 ft
- π = 3.14
Substitute the given values into the formula and solve for the surface area of one fence post:
[tex]\implies \sf SA=2 \cdot 3.14 \cdot (0.5)^2+2 \cdot 3.14 \cdot 0.5 \cdot 7[/tex]
[tex]\implies \sf SA = 1.57+21.98[/tex]
[tex]\implies \sf SA = 23.55\:\: ft^2[/tex]
Therefore, the surface area of 11 fence posts is:
= 11 × SA of one fence post
= 11 × 23.55
= 259.05 ft²