Question

Find the surface area and volume of cone. A = rs + r2 V = 1/3r2 h A cone's slant height (s) is 15 cm and its radius is 8 cm. Surface area (to the nearest tenth) = cm2 Volume (to the nearest tenth) = cm3

Answer 1

a) 483.6cm²

b) 850.1 cm³

Explanation:

Given the slant height 's' and its radius 'r' to be 15cm and 8cm respectively.

the total surface of the cone A = πrs+πr² and the volume is expressed as

V = 1/3πr²h

For the surface area of the cone;

Given parameters

radius = 8 cm and slant height s = 15 cm

Total surface area A = π(8)(15) + π(8)²

A = 90π+64π

A = 154π

If π = 3.14

A = 154(3.14)

A = 483.56cm²

A = 483.6cm²

Hence the total surface area of the cone to the nearest tenth is 483.6cm²

For the volume of the cone;

V = 1/3πr²h

Using pythagoras theorem to get the height of the cone;

l² = h²+r²

h² = l²-r²

h² = 15²-8²

h² = 225-64

h² = 161

h = √161

h = 12.69cm

V = 1/3π* (8)² * 12.69

V = 1/3π* 64 * 12.69

V = 1/3*3.14* 64 * 12.69

V = 2550.1824/3

V = 850.06 cm³

V = 850.1 cm³

Hence, the volume of the cone is 850.1 cm³ to the nearest tenth.