



 
Hi, The circumference of a circle of radius $r$ units is $2 \times \pi \times r$ units. Suppose the radius of the Earth is $r$ meters. What is the circumference? If you extend the cable so that it is $1$ meter above the surface then the radius of the circular cable is $r + 1$ meters. What is its circumference? Write down the difference of the two circumferences and simplify. Penny  


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