Question

The radius of two concentric circles are 9 cm and 12 cm respectively. Find?
the area of the circular path between the two circles.​

Answer 1

Answer:

15

Step-by-step explanation:

Area of circle = πr².

According to the given Question,

Radius of 1st circle = 9 cm.

∴ Area of 1st circle = π(9)² = 81π

Radius of 2nd circle = 12 cm.

∴ Area of 2nd circle = π(12)² = 144π.

Now,

It is said that Area is equal to the sum of the area of these two circle.

πr² = (81π + 144π)

πr² = 225π

r² = 225

r = √225

r = 15 cm.

Answer 2

Answer: Area of circular path between the circles is 229.22$cm^{2} .$

Step-by-step explanation:

Given:The radius of two concentric circles are 9 cm and 12 cm respectively.

i.e.         $r = 9cm^{2}$ and $R = 12cm^{2}$.

To find:We have to find the area of the circular path between the two circles.​

Explanation.

Step 1: Let the radius of smaller circle be r $= 9cm^{2}$and radius of bigger circle be R $= 12cm^{2}$ respectively.

Step 2: We know that the formula of area of a circle can be given by,

⇒                                      Area of circle $= \pi r^{2}$

                     Where r $=$ radius of given circle.

Step 3:So area of smaller circle whose radius is $r = 9cm^{2}$ can be given by,

⇒ Area of smaller circle $=\pi (9)^{2}$

                                        $= \pi$ × $9$ × $9$

                                        $= 81\pi$

∴  Area of smaller circle is $= 81\pi$.

Step 4:Now area of smaller circle whose radius is $R = 12cm^{2}$ can be given by,

⇒ Area of bigger circle $= \pi R^{2}$

                                       $= \pi (12)^{2}$

                                       $= \pi$ × $12$ × $12$

                                       $= 144\pi$

Step 5: To find the circular path between the two circles we have to subtract the area of smaller circle from area of bigger circle. So we have, Area of circular path between the circles $=$ Area of bigger circle $-$       Area of smaller circle

i.e. Area of circular path between the circles $= 144\pi - 81\pi$

                                                                          $= \pi (144 - 81)$

                                                                          $= \pi$ × $73$

As we know value of $\pi = 3.14$  

So, Area of circular path between the circles $= 3.14$ × $73$

                                                                           $= 229.22cm^{2}$

∴    Area of circular path between the circles is 229.22$cm^{2} .$

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Find the area of a circle whose radius is 14 cm.                        

https://brainly.in/question/2397512

Find the area of a circle whose Radius is 12 cm.

https://brainly.in/question/27619971

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