Question

When the circumference and area of a circle are numerically equal, then the diameter is numerically equal to?

Answer 1

Area = Circumference

$2\pi \: r = \pi {r}^{2}$
$2r \: = \frac{\pi \: r {}^{2} }{\pi}$
$2r \: = \: {r}^{2}$
$2r= (r) \times (r)$
$\frac{2r}{r } = r$
$2 = r \: \: \: or \: \: r = 2$
$but \: \: d = 2r \\ so \: \: \: d = 2 \times 2 \\ \: \: \: \: \: \: \: d = 4$
Therefore the diameter of the circle = 4

Answer 2

Step-by-step explanation:

Circumference of circle ≈ 2πr

Area of circle ≈ πr²

Given that 2πr ≈ πr ²

→ R ≈2

So, radius of circle =2.

Diameter = Double of radius

Diameter = 2 × 2

Diameter = 4