Question

Find the surface area of a sphere of diameter 1.4 cm.

Answer 1

Given:

diameter d = 1.4 cm.

Radius r = `d/2 = 1.4/2`

= 0.7 cm.

Use the surface-area formula for a sphere:

S = `4πr^2`.

Compute r² = (0.7)² = 0.49 cm².

S = 4 × π × 0.49

= 1.96π cm².

Numerical value:

using π ≈ 3.1416

S ≈ 1.96 × 3.1416

= 6.1575 ≈ 6.16 cm².