36 Inch Circumference To Diameter

Kritsin Trapp writes math articles and how to solve diverse problems.

Read on to learn how to calculate the circumference of a circle. — Read on to larn how to summate the circumference of a circle.

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Circumference of Circle

Understanding what the circumference of a circle is, equally well every bit how to calculate the circumference of a circle, is a relatively like shooting fish in a barrel geometry principle. By post-obit the circumference problems and solutions in the Geometry Help Online department below, you should easily be able to grasp the concept of circumference.

Past following along with the examples given and taking the online Math Made Easy! geometry quiz for the circumference of a circumvolve, you will exist able to complete your geometry homework on this topic in a snap.

Geometry Help

Area of a Circle
Surface Surface area of a Cylinder

Circumference of Circle Formula

The circumference of a circle is just the altitude effectually a circle. Sometimes information technology is referred to as the perimeter, although the term perimeter is usually reserved for the measure out of a altitude around a polygon.

The equation for the circumference of a circle can be written in two means:

C = 2πr
C = πd

Where: r represents the radius of the circumvolve, and d represents a circumvolve's diameter.

Recall that the radius is the distance from the middle of the circumvolve to a betoken on the edge of a circumvolve, and the bore is the largest distance beyond a circle. The bore is e'er twice the length of the radius.

When calculating the circumference with a known radius, apply the starting time version of the circumference formula shown; when the bore is known, utilise the 2nd version of the circumference formula shown.

Modern-Twenty-four hour period Uses for Circumference

Did you know that the circumference of the Earth was first calculated more than 2200 years ago by the Greek mathematician Eratosthenes?

Knowing how to summate circumference is used in many fields of study, including:

engineers
architects
carpenters
artists

High School Geometry Assistance: Terms

Circumvolve Terms to Know:

Pi: symbol for pi is π and it equals about three.fourteen
Radius: The distance from the heart of a circle to an border
Radii: The plural for radius.
Diameter: The distance from one border of a circle to another edge going through the center.
Circumference: The distance effectually a circle; the perimeter of a circle.

Curl to Continue

Math Fabricated Easy! Tip

If yous take problem remembering geometry terms, it helps to think of other words from the same root with which you may be more familiar.

For case, the Latin root of the word circumference is circum, pregnant around. Circum is now considered a prefix also meaning around or round about.

Hither is a list of words that come from the root/prefix circum that can help you remember that circumference the altitude of mensurate around a circle:

Circus - (from the root circum) usually held in a circular arena
Circle - (from the root circum) a round shape
Circumvent - to become around or bypass; to avoid
Circumstances - weather condition surrounding an effect
Circumnavigate - to fly or sail effectually

Geometry Help Online: Circumference

Check out four common types of geometry homework problems and solutions involving the circumference of circles.

#1 Find the Circumference of a Circumvolve Given the Radius

Problem: Discover the circumference of a circle with a radius of 20 cm.

Solution: Plug in 20 for r in the formula C = two πr and solve.

C = (2)(π)(20)
C = 40π
C = 125.vi

Answer: A circle with a diameter of 20 cm. has a circumference of 125.half-dozen cm.

#two Find the Circumference of a Circle Given the Diameter

Problem: Find the circumference of a circumvolve with a diameter of 36 in.

Solution: Simply plug in 36 for d in the formula C = πd and solve.

C = (π)(36)
C = (3.14)(36)
C = 113

Answer: The circumference of a circle with a bore of 36 in. is 113 in.

#3 Find the Radius of a Circle Given the Circumference

Problem: What is the radius of a circle with a circumference of 132 ft.?

Solution: Since we are trying to determine the radius, plug in the known circumference, 132, for C in the formula C = 2πr and solve.

132 = 2πr
66 = πr (divide both sides by two)
66 = (three.14)r
r = 21 (divide both sides by 3.14)

Answer: A circumvolve with a circumference of 132 ft. has a radius of about 21 ft.

#four Discover the Circumference of a Circumvolve Given the Area

Problem: Notice the circumference of a circle that has an expanse of 78.5 m. squared.

Solution: This is a two-footstep problem. First, since nosotros know the area of the circle, nosotros can figure out the radius of the circle by plugging in 78.five for A in the expanse of a circle formula A = πrⁱⁱ and solving:

78.v = πr²
78.5 = (3.14)rⁱⁱ
25 = r^two (divide both sides by 3.14)
r = 5 (accept the square root of both sides)

At present that we know the radius is equal to 5 m. nosotros tin substitute v in for r in the formula C = 2πr and solve:

C = 2π(five)
C = (two)(3.14)(5)
C = 31.iv

Answer: A circle with an expanse of 78.5 1000. squared has a circumference of 31.four 1000.

Exercise You Need More than Geometry Help Online?

If you still need help with other geometry problems virtually the circumference of a circle, please ask in the comment section beneath. I'll exist glad to help out and may even include circumference math problem in the trouble/solution section above.

unknown on March 13, 2018:

cheers so much this article was so helpful i very much cheers!

Kristin Trapp (author) from Illinois on March 06, 2012:

I'one thousand glad to aid SmartAndFun.

SmartAndFun from Texas on March 06, 2012:

LOL, my daughter (the smarter one) figured that out. I am following you and so that I'll be sure to be able to detect yous once again. Dd is doing fairly OK in geometry this semester, only final semester (algebra) most of her homework sessions ended in tears. She got a 45 on an algebra assignment that she, my married man and I all worked on together for iii hours. LOL, we idea betwixt the 3 of united states she'd get at least a C. We volition demand you once again for sure! Cheers!

Kristin Trapp (author) from Illinois on March 06, 2012:

Yous are very welcome SmartandFun. Although looking back over my answer, somehow my pi symbol was replaced with a question mark. I am glad yous could follow along.

SmartAndFun from Texas on March 06, 2012:

Thank you and so much, KTrapp, you are a life saver! I was able to go over your answer with my girl this morning earlier school, and nosotros both get it at present! She and I are both "arts and letters" blazon people and accept a difficult fourth dimension with math. I feel terrible when she asks me for help. I endeavor to aid but truthfully she is alee of me in the math dept. I run into those symbols and letters (like the m) and my encephalon but freezes up. Thanks so much for helping us both! You are wonderful!

Kristin Trapp (author) from Illinois on March 06, 2012:

Smartandfun - Cheers for your question. I think I tin can assistance both you and your daughter. First, let's talk about Expanse. The Area of anything (circle, square, triangle, etc.) is ever in terms of units squared. For example, a foursquare where each side is 2inches has a perimeter (distance around) of 8inches and an area of 4inches squared. Information technology'due south squared because we multiplied 2inches Ten 2 inches which = 4inches squared.

In example #four the "m" simply represents the units (i.e. meters). It is "m squared" since the 78.5 represents the Area of the circle, and Area is always units squared.

I don't know the type of measurement (units) for your daughter'due south specific math problem, simply whatever it is,those units would also squared.

But let's not get hung up on the units. What we know is that the Area of the circle is 200.96 and nosotros desire to effigy out the circumference. If you look at the equations for the Area of a circumvolve and the Circumference of a circle, they both have r (radius) in them. Then if we could figure out the radius of the circle knowing the Area, then nosotros could plug the radius of the circumvolve into the Circumference equation in order to find the circumference.

And so let'southward do that. We will let ?=3.14 to solve the problem:

step i: A=2(?)r ^squared

step 2: 200.96 = ?r ^squared

pace 3: 64=r ^squared (divide both sides of equation by 3.fourteen)

footstep 4: 8=r (have the square root of both sides of the equation)

Now that nosotros know the radius of the circumvolve is 8 units nosotros can substitute 8 for r into the circumference equation as follows:

C=two?r

C= 2?8 (we know r = 8 so plug it into the equation)

C=16? (multiple ii X 8 to get 16)

C=16(3.xiv) (let ? = 3.fourteen to solve)

C=50.24units

Therefore, a circle with an Area of 200.96 units^squared has a radius of viii units and a Circumference of 50.24 units.

I promise this helps. Thanks for asking.

SmartAndFun from Texas on March 05, 2012:

I am trying to help my 7th grade daughter learn how to effigy the circumference of a circle when all that is known is the area, but I'yard the blind leading the blind, LOL. I'm looking at the final case, and I am not understanding at all. The instance yous give has an area of 78.5 yard squared. What do we do if the area in her question is non k or squared? What does the m represent? The surface area in her question is 200.96. How does that plug into the formula? I do not get information technology at all! Thank you lot!

shan on February 15, 2012:

I Become It

Kristin Trapp (author) from Illinois on Jan 23, 2012:

Fizzywoz - If yous look at examples #ane-#4 at the end of the commodity you can see how numbers are plugged into the equation. Y'all volition unremarkably simply plug in a known radius into the equation to figure out the circumference or yous may plug in a known circumference to determine the radius. Let me know if you have whatsoever other questions. I capeesh your feedback.

Fizzywoz on Jan 23, 2012:

You lot havn't really explained what yous do in the equations if you lot could just exercise that this article would be even more helpful :)

Kristin Trapp (author) from Illinois on October 24, 2011:

When my kids would tell me they weren't going to demand the math that was existence forced upon them, I always told them they were right. They probably never were going to demand that verbal math, but the value for most kids is in the exercise information technology gives their brains. Near colleges similar to run into three-4 years of loftier school math so most kids have no selection but to find their style through it. No skating immune anymore. The times they are a-changin'.

Arlene V. Poma on October 23, 2011:

k, k, yard! I didn't need this stuff! I skated. Only in California, you have to pass English and math to graduate. Ewwwwww. I would have flunked the math for sure!

Kristin Trapp (writer) from Illinois on October 23, 2011:

I'm glad y'all call back Arlene, afterall you never know when y'all might need to effigy out the circumference of something when y'all merely know its radius. I think this is what makes frustrated math students ask, "when am I ever going to need this?"

Arlene Five. Poma on October 23, 2011:

I am pulling my pilus out, simply I practice remember how to do this.

Kristin Trapp (author) from Illinois on October 23, 2011:

Thank you Stephanie. A practiced mental attitude, as you put it, definitely helps when learning math. I think sometimes the pace in loftier school is too fast for some kids, especially when it is their outset fourth dimension ever learning some of these concepts.

Stephanie Das from Miami, US on October 23, 2011:

Of all math forms, geometry is the one that I accept found most useful in my everyday life. These are little skills that we need to exist reminded of from time to time. It also helps that I understand the importance of math and have a better attitude towards it now than I did when I was in loftier schoolhouse! Voted upward and useful.