Question

The area between two concentric circles is 346.5 sq.cm. and the circumference of the inner circle is 88 cm. Calculate the radius of the outer circle.

Answer 1

Answer:

Radius of the outer circle is 17.5 cm

Step-by-step explanation:

Let R and r be radii of outer and inner circles.

circumference of the innner circle=88 cm

$2\:\pi\:r=88\\\\2*\frac{22}{7}*r=88\\\\\frac{r}{7}=2\\\\r=14\:cm$

Area betwen two concentric circles=346.5 sq.cm

$\pi(R^2-r^2)=346.5\\\\\frac{22}{7}(R^2-r^2)=346.5\\\\(R^2-r^2)=(346.5).\frac{7}{22}\\\\(R^2-r^2)=(31.5).\frac{7}{2}\\\\R^2-(14)^2=(15.75)7\\\\R^2=110.25+196\\\\R^2=306.25\\\\R=17.5 cm$

Answer 2

Answer:

Step-by-step explanation: