Question

22. The area between two concentric circles having radii 70 cm and 50 cm is
(a) 7547 cm
(1) 75540 cm
(c) 7540 cm
(1) 7543 cm​

Answer 1

Answer:

7540

Step-by-step explanation:

$\pi ( {r}^{2} - {r}^{2} ) \\ \pi( {70}^{2} - {50}^{2} ) \\ \pi(4900 - 2500) \\ \pi \times 2400 \\ 7539.82 \: {cm}^{2}$

Answer 2

Given:

The radius of larger circle ($R$) = $70$ cm

The radius of smaller circle (r) = $50$ cm

To find:

The area between two concentric circles

Formula used:

The area between two concentric circles = $\pi (R^{2}\;-\;r^{2} )$ square units

Step-by-step explanation:

The area between two concentric circles = $\pi (R^{2}\;-\;r^{2} )$ square units

⇒ The area between two circles = $\frac{22}{7} (70^{2}\;-\;50^{2} )$ $cm^{2}$

⇒ The area between two circles = $\frac{22}7\;(4900\;-\;2500)$ $cm^{2}$

⇒ The area between two circles = $\frac{22}7\;\times\;2400$

⇒ The area between two circles = $7542.8\;\;cm^{2}$

Answer:

Therefore, the area between two concentric circles having radii $70$ cm and $50$ cm is option (d) $7543\;\;cm^{2}$