School Y.
asked • 06/08/20Math help please
Find the circumference of each circle, use 3.14 for . Include units and round to the nearest tenth. Show work.
Only 3, 4, 5 and 6
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1 Expert Answer
Sindhuja R. answered • 06/08/20
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New to Wyzant
Experienced Tutor specializing in Geometry
3) Given diameter(d) = 13km => r = 13/2
The circumference of the circle= 2 * Pi * r
= 2 * 3.14 * 13/2
= 3.14* 13 (cancelling numerator 2 and denominator 2)
= 40.82.
= 40.8 km (rounding to nearest tenth).
4) Given, radius(r) = 3.5 ft
The circumference of the circle= 2 * Pi * r
= 2 * 3.14 * 3.5
= 21.98
= 22 ft (rounding to nearest tenth).
Similarly try solving the remaining 5th and 6th questions, i am available to clarify any doubts.
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Lauren G.
The basic equations that will be useful for these problems are the following: A = pi*r^2 (Where A = Area; pi = 3.14; and r = radius) as well as the equation, C = 2*pi*r (Where pi = 3.14; and r = radius) Let's take a look at the problems: #3 - This picture shows a circle with a diameter of 13 km, and is asking for the circumference. Let's use the second equation. One common rule to remember in geometry is that 2*r = d, so the equation can also be written as C = d*pi Using that thought process, the circumference for this circle is: C = (13 km)*(3.14) = 40.82 km #4 - For this circle, we are given the fact that the circle has a radius of 3.5 ft. Let's use the second equation again, but this time with the r instead of d. This will give us... C = 2*(3.14)*(3.5 ft) = 21.98 ft for the circumference of this circle. #5 Using the same equation as number #3, this situation is nearly the same, without the image showing the situation. C = d*pi = (9 in)*(3.14) = 28.26 in #6 - This situation is the same as question #4, except it has different units. C = 2*pi*r = 2*(3.14)*(5 mm) = 31.4 mm06/08/20