Proportionality>Describing Pi as the Ratio of Circumference to Diameter(TEKS.Math.7.5.B)
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Texas 7th Grade Math › Proportionality>Describing Pi as the Ratio of Circumference to Diameter(TEKS.Math.7.5.B)
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1
A circle has diameter 8 inches and circumference 25.12 inches
How does the ratio $C/d$ compare to $\pi$?
Less than $\pi$
About half of $\pi$
About twice $\pi$
Approximately equal to $\pi$
Explanation
$\pi$ is the constant ratio $C/d$ for any circle. Compute $C/d = 25.12/8 = 3.14 \approx 3.14159 = \pi$. Thus the ratio is approximately equal to $\pi$, showing why $\pi$ underlies circle measurements.