Question

the areas of two concentric circles are 13 86 CM square and 18 86.5 cm square respectively find the width of the Ring​

Answer 1

Answer:

3.5 cm

Step-by-step explanation:

Given that area of inner concentric circle = 1386 $cm^{2}$

We know that area of circle = $\pi r^{2}$

So, 1386 = $\pi r^{2}$

Taking π as 22/7 we get,

$1386 = \frac{22}{7} \times r^{2}$

=> $r^{2}$ = 1386 × 7/22

=> $r^{2}$ = 441

=> r = √441

=> r = 21

Similarly, radius of other circle =

R =

$\sqrt{1886.5 \times \frac{7}{22} } \\\\=\sqrt{600.25} \\\\=24.5$

So, the width of ring formed = R - r

= 24.5 - 21

= 3.5 cm

Answer 2

$\bold{\huge{\underline{Question}}}$

the areas of two concentric circles are 13 86 CM square and 18 86.5 cm square respectively find the width of the Ring​

$\bold{\huge{\underline{Solution-}}}$According to the question we know that the area of two concentric circles are 1386 Cm², and radius of other circle is 1886.5cm² Here we need to use the formula, πr² "for finding the area of circle" ,

Now,

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

We know that area of circle = 1386

The value of π = 22/7

Then, putting the above values in Formula

$\bf \: 1386 = \frac{22}{7} \times {r}^{2}$

$\bf \: {r}^{2} = 1386 \times \frac{7}{22}$

$\bf {r}^{2} = 441 \\ \\ \bf \: r = \sqrt{441} \\ \\ \bf \: r \: = 21...................(1)$

then, We know that Radius of other circle is

Area = πR²

$\bf \: R = \sqrt{1886.5 \times \frac{7}{22} }$

$\bf \: R = 24.5.............(2)$

Then,

The wide of ring = Second equation - First equation

$\bf \implies \: 24.5 - 21$

$\bf \implies3.5\:cm$