Question

Help please!!!!!!!!!!!!​

Answer 1

Q1)

GIVEN :-

• Diameter = 9m ⇒ Radius (r) = 9/2 = 4.5m
• Slant height (l) = 13m

TO FIND :-

• Surface area of the whole figure.

FORMULAES TO KNOW BEFORE SOLVING :-

• Curved surface area of cone =
  `\pi rl` (where r = radius & l = slant height)
• Curved surface area of hemisphere =
  `2\pi r^2` (where r = radius)

PROCEDURE :-

In the figure , the cone is mounted on a hemisphere.

⇒ Radius of cone = Radius of hemisphere = 4.5m

Total surface area of the figure = Curved surface area of both cone & hemisphere.

⇒

• Curved surface area of cone =
  `\pi rl = 3.14 * 4.5 * 13 = 183.69m^2` ≈ 183.7m²

• Curved surface area of hemisphere =
  `2\pi r^2 = 2 * 3.14 * (4.5)^2 = 127.17m^2` ≈ 127.1m²

∴ Total surface area = 183.7 + 127.1 = 310.8m²

Q2)

GIVEN :-

• Radius (r) = 3km

TO FIND :-

• Volume of hemisphere
• Surface area of hemisphere

FORMULAES TO KNOW BEFORE SOLVING :-

• Volume of hemisphere =
  `(2)/(3) \pi r^3` (where r = radius)
• Surface area of hemisphere =
  `2\pi r^2` (where r = radius)

PROCEDURE :-

Volume of hemisphere =
`(2)/(3) \pi r^3 = (2)/(3) * 3.14 * (3)^3 = 56.52km^3` ≈ 56.5km³

Surface area of hemisphere =
`2\pi r^2 = 2 * 3.14 * (3)^2 = 56.52km^2` ≈ 56.5km²