Respuesta :

We need radius

  • πr²h=1715
  • πr²(18)=1715
  • r²=30.3
  • r=5.5cm

Now

LSA

  • 2πrh
  • 2π(5.5)(18)
  • 11(18)(3.14)
  • 198(3.14)
  • 622.72cm²

Answer:

813.4 cm² (nearest tenth)

Step-by-step explanation:

Volume of a cylinder

[tex]\sf V=\pi r^2 h \quad\textsf{(where r is the radius and h is the height)}[/tex]

Given:

  • h = 18cm
  • V = 1715 cm³

Use the Volume of a Cylinder formula and the given values to find the radius of the cylinder:

[tex]\implies \sf 1715=\pi r^2 (18)[/tex]

[tex]\implies \sf r^2=\dfrac{1715}{18 \pi}[/tex]

[tex]\implies \sf r=\sqrt{\dfrac{1715}{18 \pi}[/tex]

Surface Area of a Cylinder

[tex]\sf SA=2 \pi r^2 + 2 \pi r h \quad\textsf{(where r is the radius and h is the height)}[/tex]

Substitute the given value of h and the found value of r into the formula and solve for SA:

[tex]\implies \sf SA=2 \pi \left(\sqrt{\dfrac{1715}{18 \pi}\right)^2 + 2 \pi \left(\sqrt{\dfrac{1715}{18 \pi}\right)(18)[/tex]

[tex]\implies \sf SA=2 \pi \left(\dfrac{1715}{18 \pi} \right) + 36 \pi \left(\sqrt{\dfrac{1715}{18 \pi}\right)[/tex]

[tex]\implies \sf SA=\dfrac{1715}{9} + 36 \pi \left(\sqrt{\dfrac{1715}{18 \pi}\right)[/tex]

[tex]\implies \sf SA=813.3908956...[/tex]

Therefore, the surface area of the cylinder is 813.4 cm² (nearest tenth)