Question

Part I: Measuring Parts of a Circle

Answer 1

Answer:

case a) The approximate circumference of circle is $5.9\ units$ and the ratio of circumference to Diameter is $\frac{C}{D}=2.95$

case b) The approximate circumference of circle is $6\ units$ and the ratio of circumference to Diameter is $\frac{C}{D}=3$

case c) The approximate circumference of circle is $6.24\ units$ and the ratio of circumference to Diameter is $\frac{C}{D}=3.12$

Step-by-step explanation:

we know that

The approximate circumference of each circle, is equal to the perimeter of each inscribed polygon

case A) the figure is an inscribed pentagon

step 1

Find the approximate circumference of circle

The perimeter of the pentagon is equal to

$P=5s$

where

$s=1.18\ units$

substitute

$P=5(1.18)=5.9\ units$

therefore

The approximate circumference of circle is $5.9\ units$

step 2

Find the ratio of circumference to Diameter

we know that

The radius is half the diameter so

$D=2r=2(1)=2\ units$

The ratio is equal to

$\frac{C}{D}=5.9/2=2.95$

case B) the figure is an inscribed hexagon

step 1

Find the approximate circumference of circle

The perimeter of the hexagon is equal to

$P=6s$

where

$s=1\ units$

substitute

$P=6(1)=6\ units$

therefore

The approximate circumference of circle is $6\ units$

step 2

Find the ratio of circumference to Diameter

we know that

The radius is half the diameter so

$D=2r=2(1)=2\ units$

The ratio is equal to

$\frac{C}{D}=6/2=3$

case C) the figure is an inscribed dodecahedron

step 1

Find the approximate circumference of circle

The perimeter of the dodecahedron is equal to

$P=12s$

where

$s=0.52\ units$

substitute

$P=12(0.52)=6.24\ units$

therefore

The approximate circumference of circle is $6.24\ units$

step 2

Find the ratio of circumference to Diameter

we know that

The radius is half the diameter so

$D=2r=2(1)=2\ units$

The ratio is equal to

$\frac{C}{D}=6.24/2=3.12$

Conclusion

We  know that

The exact value of the ratio $\frac{C}{D}$ is equal to

$\frac{\pi D}{D}=\pi$

The approximate value of the circumference will be closer to the real one when the number of sides of the inscribed polygon is greater