Question

The area between two concentric circles is 346.5 cm^2 and the circumference of the inner circle is 88cm .calculate the radius of the outer circle

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

17.5 cm

Step-by-step explanation:

Circumference = $2\pi r$

Since we are given that  the circumference of the inner circle is 88cm

So,  $88= 2 \times \frac{22}{7} r$

$44 \times \frac{7}{22}= r$

$14= r$

Thus the inner radius = 14 cm

Area between concentric circle = Area of outer circle - Area of inner circle

                                                  =$\pi R^2 -\pi r^2$

Since we are given that The area between two concentric circles is 346.5 sq. cm.

So, $346.5=\frac{22}{7}(R^2 -14^2)$

$346.5\times \frac{7}{22}=R^2 -14^2$

$110.25=R^2 -196$

$306.25=R^2$

$17.5=R$

Hence the radius of outer circle is 17.5 cm.