



 
Hi Terry, In my diagram the length of $CA$ is 9 feet and $D$ is the midpoint of $AB.$ The measure of angle $BCA$ is $\frac{360^o}{8} = 45^o$ and hence the measure of angle $DCA$ is $22.5^o.$ If the side length $BA$ is $s$ feet then \[\sin(DCA) = \sin(22.5^o) = \frac{AD}{CA} = \frac{s/2}{9}\] and hence \[\frac{s}{2} = 9 \times \sin(22.5^o) = 3.444 \mbox{ feet.}\] Thus the side length $AB$ is $2 \times 3.444 = 6.888$ feet which is approximately $6$ feet $10$ and $\frac{11}{16}$ inches. Penny  


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