Question

A. Directions: Find the surface of the following. Round your answer to nearest

hundredths. (Use n = 3.14) Write your answer in your notebook.
1) cone with radius of 15 cm and slant height of 12 cm
2) cone with radius of 8 cm and slant height of 11 cm
3) sphere with radius of 3.2 cm
4) sphere with diameter of 6 cm​

Answer 1

1. S.A of a cone = 565.56 cm².

2. S.A of a cone = 276.496 cm².

3. S.A of a sphere = 128.696 cm².

4. S.A of a sphere = 113.112 cm².

Explanation:

Given the following data;

1. Radius, r = 15cm

Slant height, l = 12cm

Mathematically, the surface area of a cone is given by the formula;

Surface area of a cone = πrl

Substituting into the formula, we have;

S.A of a cone = 3.142 * 15 * 12

S.A of a cone = 3.142 * 180

S.A of a cone = 565.56 cm²

2. Radius, r = 8cm

Slant height, l = 11cm

Surface area of a cone = πrl

S.A of a cone = 3.142 * 8 * 11

S.A of a cone = 3.142 * 88

S.A of a cone = 276.496 cm²

3. Radius, r = 3.2 cm

Mathematically, the surface area of a sphere is given by the formula;

Surface area of a sphere = 4πr²

Substituting into the formula, we have;

S.A of a sphere = 4 * 3.142 * 3.2²

S.A of a sphere = 4 * 3.142 * 10.24

S.A of a sphere = 40.96 * 3.142

S.A of a sphere = 128.696 cm²

4. Diameter, d = 6cm

Radius, r = diameter/2 = 6/2 = 3 cm

Surface area of a sphere = 4πr²

S.A of a sphere = 4 * 3.142 * 3²

S.A of a sphere = 4 * 3.142 * 9

S.A of a sphere = 36 * 3.142

S.A of a sphere = 113.112 cm²