question_answer 31)

Find the circumference of the inner and the outer circles as shown in the adjoining figure? \[\left( \text{Take }\pi =\text{3}.\text{14} \right)\]

Answer:

                Radius of inner circle \[=\text{19}-\text{1}0=\text{9 m}\] \[\therefore \]                  Circumference of the inner circle \[=2\pi r\] \[\text{= 2  }\!\!\times\!\!\text{  3}\text{.14  }\!\!\times\!\!\text{  9 m}\]                 \[\text{= 56}\text{.52 cm}\] Radius of the outer circle \[=\text{19 m}\] \[\therefore \] Circumference of the outer circle \[=2\pi r\]   \[\text{= 2  }\!\!\times\!\!\text{  3}\text{.14  }\!\!\times\!\!\text{  19 m}\] \[\text{= 119}\text{.32 m}\]