Question

2 concentric circles

Answer 1

Answer:

3465 sq. cm

Step-by-step explanation:

Answer 2

Answer:

The area of shaded region is 1102.5π cm² or 6463.6 cm²

Step-by-step explanation:

We are a given a concentric circle with center O. Please see the attachment.

Radius of bigger circle (R) = 42 cm

Radius of smaller circle (r) = 21 cm

Formula:

• Area of circle $=\pi r^2$
• Area of sector $=\dfrac{\theta}{360^{\circ}}\pi r^2$

Area of bigger circle $=\pi R^2=\pi (42)^2\Rightarrow 1764\pi \ cm^2$

Area of smaller circle $=\pi r^2=\pi (21)^2\Rightarrow 441\pi \ cm^2$

Area of sector ABDC$=\dfrac{60}{360}\pi(42^2-21^2)\Rightarrow 220.5\pi\ cm^2$

Area of shaded region = Area of bigger circle - Area of smaller circle - Area of sector ABDC.

Area of shaded region $=1764\pi - 441\pi -220.5\pi \Rightarrow 1102.5\pi\ cm^2$

Hence, The area of shaded region is 1102.5π cm² or 6463.6 cm²