



 
Hi Terry, The circumference of a circle is 2π × r where r is the radius. I want to work in feet so using your number of 25,000 miles the circumference of the earth in feet is
so
If the radius is increased by 1 foot the new circumference is
Use the value of r obtained above, calculate the new circumference and compare it to 25,000 × 5,280. Penny  


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