Question

Find the area enclosed between two concentric circles of radii 4cm and 3cm

Answer 1

Answer:22$cm^{2}$

Step-by-step explanation:

• To find the area between two concentric circle of radii 4cm and 3cm we need to subtract the area of the smaller circle with area of bigger circle.

• Area of circle with radii 4cm=$\pi r^{2}$

                                                         =$\frac{22}{7}*(4)^{2}$

                                                         =$\frac{22}{7}*16$

                                                         =$\frac{352}{7}cm^{2}$

• Area of circle with radii 3cm=$\pi r^{2}$

                                                      =$\frac{22}{7}*(3)^{2}$

                                                      =$\frac{22}{7}*9$

                                                      =$\frac{198}{7}cm^{2}$

• Area between two circles=$(\frac{352}{7}-\frac{198}{7}) cm^{2}$

                                                   =$\frac{154}{7}cm^{2}$

                                                   =22$cm^{2}$

• Hence,area between the two circles=22$cm^{2}$





                                                     



         

Answer 2

Answer:

The enclosed area is $22\:cm$.

Step-by-step explanation:

Given,

The radius of the circle $4\:cm$ and $3\:cm$.

Thus,

The area of the circle with $4\:cm = \pi R^{2}$

The area of the circle with $3\:cm = \pi r^{2}$

The area enclosed = The area of the circle with $4\:cm$ - The area of the circle with $3\:cm$

The area enclosed $= \pi R^{2} - \pi r^{2}$

$= \pi (R^{2} -r^{2})$

As it is known,

$\pi = \frac{22}{7}\\R = 4\\r = 3$

Putting all the values,

$= \frac{22}{7}(16-9)\\= 22$

Thus, the enclosed area is $22\: cm$.

#SPJ3